Sensor device for containers of liquid substances

ABSTRACT

An optical sensor device for detection of a characteristic of a liquid substance comprises a device body having an inner surface and an outer surface, one portion of the outer surface of the device body being designed to be in contact with the liquid substance, and the inner surface of the device body being designed to be isolated from the liquid substance. 
     Associated to the device body is a detection arrangement, which comprises an emitter and a receiver of a given optical radiation. A first portion of the device body is made of a material designed for propagation of the given optical radiation, the emitter and the receiver being optically coupled to the inner surface of the device body in the first portion. The first portion of the device body is shaped to contribute to propagation of the given optical radiation, from the emitter to the receiver, in such a way that the given optical radiation is propagated through the first portion of the device body towards the receiver, at an angle and/or with an intensity that are/is variable as a function of a characteristic of the liquid substance. 
     The detection arrangement comprises an optical module, which includes a structure for support and electrical connection of the emitter and the receiver, which is configured as a part separate from the device body. The supporting and electrical-connection structure includes a plurality of bodies made of electrically insulating material overmoulded on electrical-connection elements made of electrically conductive material.

FIELD OF THE INVENTION

The present invention relates to sensor devices used in combination withgeneric containers designed to contain a liquid substance, and has beendeveloped with particular reference to sensor devices that comprise anoptical arrangement for detection of at least one characteristicquantity of the liquid substance.

The invention finds a preferred application in the vehicle sector or inthe sector of systems in general that are equipped withinternal-combustion, or endothermic, engines, in particular incombination with hydraulic systems or tanks designed to convey orcontain a substance, such as a fuel or else a liquid solution necessaryfor operation of an exhaust-gas treatment system of aninternal-combustion engine, where the aforesaid optical arrangement isused for detecting at least one concentration of the substance orsolution.

PRIOR ART

For the purposes of checking substances contained in generic containersit is common to use sensors of characteristics such as level,temperature, quality, etc.

A typical example is represented by tanks containing liquid substances,which belong to exhaust-gas emission systems of some types of vehicles,devised for the purposes of reduction of release of nitrogen oxides(NOx) into the atmosphere. A particularly widespread system for thispurpose is based upon the process known as SCR (Selective CatalyticReduction), which enables reduction of nitrogen oxides of the gases viainjection of a reducing liquid substance into the exhaust line. Thesetreatment systems presuppose that the reducing agent is dosed andinjected into the flow of the exhaust gases in order to convert nitrogenoxide (NOx) into nitrogen (N₂) and water (H₂O). The reducing substanceis typically constituted by a solution of water and urea.

Proper operation of these systems presupposes that the correspondingcontrol unit recognises the presence of the reducing substance withinthe tank, in particular measuring the level thereof and warning of thepossible need for topping up. In some cases detection is also providedof information concerning characteristics of the reducing substance,such as characteristics linked to its composition.

For instance, WO 2010/151327 describes a tank for a reducing substance,mounted on which is a level sensor, configured for generating aradiofrequency signal in a resonant circuit and for propagating theresulting electromagnetic radiation in the substance, as well as fordetecting changes in the impedance and resonance of the aforesaidcircuit, where such changes are considered as being representative ofchanges in the conductivity and dielectric properties of the substancethat are proportional to the amount of the substance, i.e., its level.The level sensor may be provided with capacitive and/or resistive probesfor detecting the quality of the substance. On a side wall of the tankthere may possibly be mounted a further sensor of an electro-opticaltype, designed to detect other characteristics of the substance. Thisfurther optical sensor is submerged by the substance when the latter hasa sufficient level in the tank. An emitter directs a light beam towardsa prism, which constitutes a tip of the sensor and is configured forrefracting the radiation into the liquid, the reflected light beingdetected by a receiver. The reflected light is considered directlyproportional to the refractive index of the substance, which makes itpossible to determine whether the substance contained is water or asolution of urea, and to determine the concentration of the solution.

Optical sensors of this type are generally complicated to produce andassemble, in particular in view of the need to ensure proper positioningof the emitter and of the receiver.

OBJECT AND SUMMARY OF THE INVENTION

The aim of the present invention is basically to overcome the drawbackshighlighted above, in a simple, economically advantageous, and reliableway.

The above and other purposes still, which will emerge more clearlyhereinafter, are achieved according to the present invention by a sensordevice having the characteristics specified in the annexed claims. Theclaims form an integral part of the technical teaching provided hereinin relation to the invention.

In a device according to the invention, an optical module is provided,which integrates at least one emitter and at least one receiver of apredetermined optical radiation, which are supported by a supporting andelectrical-connection structure that is configured as a part separatefrom a body of the device and that includes one or more supportingbodies made of electrically insulating material associated, preferablyvia overmoulding, to electrical-connection elements made of electricallyconductive material. In this way, the aforesaid supporting andelectrical-connection structure, and hence the optical module, can beobtained in a simple and precise way, with the module itself that can beeasily pre-assembled, tested, and subsequently mounted on the body ofthe device and electrically connected in a simple, fast, and automatableway.

According to a preferential embodiment, such as the one referred to inClaim 2, the aforesaid structure includes a plurality of bodies formedseparately, but joined together exploiting the sameelectrical-connection elements as those used for transmission of thesignals coming from the emitter and the receiver of optical radiationdetermines, to the advantage of simplicity of production and compactnessof the module. Advantageously, the aforesaid connection elements may beelastically deformable or flexible in order to enable recovery ofproduction and assembly tolerances, thereby guaranteeing in any casecorrect position of the emitter and the receiver. According theimplementation requirements, the emitter and the receiver may be mountedon opposite faces of two generally opposite lateral bodies of theaforesaid structure.

Other embodiments of the supporting and connection structure are on theother hand possible, such as the ones referred to in Claim 3, based, forexample, upon the use of a flexible circuit support or PCB, whichincludes or integrates connection elements, associated to which (e.g.,overmoulded or glued) are a plurality of distinct bodies (such as acentral body and two lateral bodies), or a plurality of moulded bodiesmade of an electrically insulating polymer and a plurality ofelectrical-connection elements made of a conductive polymer, the bodiesand connection elements being comoulded or overmoulded on one another,or may again be distinct bodies, obtained, for example, via moulding,associated to connection elements obtained via blanking. In preferredembodiments, a plurality of bodies of the supporting andelectrical-connection structure are connected together (e.g., via atleast part of the electrical-connection elements or else viaintermediate body portions) so that it is possible to vary a relativeposition thereof during assembly of the optical module on the devicebody, in order to enable proper positioning of the emitter and of thereceiver.

According to a preferential embodiment, such as the one referred to inClaim 4, a body of the device is shaped to define a positioning sitethat guarantees maintenance of the correct operating position of theoptical module, and hence of the emitter and of the receiver, to theadvantage of ease and precision of assembly, as well as precision ofdetection. Advantageously, one or more projecting elements of thepositioning site may function as positioning elements for the opticalmodule and/or as optical elements exploited for propagation of the givenoptical radiation.

According to a preferential embodiment, such as the one referred to inClaim 5, at least one body of the supporting and electrical-connectionstructure is shaped so as to define means for positioning and/orblocking with respect to the optical site, in order to increase furtherthe precision of assembly and of detection by the optical arrangement.

According to a preferential embodiment, such as the one referred to inClaim 6, a blocking and/or positioning member is purposely provided,designed to co-operate with at least one projecting element of theaforesaid site in order to ensure maintenance of the correct position ofthe optical module and render assembly thereof easy and fast. Theblocking and/or positioning member may be variously configured, forexample as referred to in Claim 7, according to the requirements andconfigurations of assembly of the optical module.

In preferential embodiments, such as the ones specified in Claim 8, theat least one emitter consists of a single emitter, and the at least onereceiver comprises at least two receivers in positions generally setalongside one another. This solution is particularly advantageous whenthe detection of the characteristic of interest of the fluid substanceis based upon the principle of the critical angle of total reflection,according to which the optical radiation of interest can be reflected atan angle that is variable as a function of the characteristic ofinterest. The use of two receivers in positions set alongside oneanother prevents the need for use of a single and more complex andcostly receiver, such as a receiver of the CMOS-array type.

The relative arrangement between emitter and receiver may differ, forexample as specified in Claim 9, according to the plastic material usedfor the interface wall between solid and liquid, the type of opticalradiation (i.e., the type of emitter) that is to be adopted, and thetype of substance.

The shielding means provided according to preferential embodiments, suchas the ones referred to in Claim 10, prevent any undesired opticalradiation from possibly adversely affecting the precision and quality ofthe detections made via the optical arrangement. For instance, ashielding element may be used for preventing part of the opticalradiation emitted by the emitter from possibly reaching the receiverdirectly, without contributing to detection of the characteristic ofinterest and instead adversely affecting the aforesaid detection.Advantageously, this shielding element may belong to the optical module,to further advantage of compactness and ease of assembly, this elementbeing able, if need be, also to be exploited for purposes of positioningof the module itself. Likewise, an optical shield may be used foreliminating or minimising the negative effects that ambient light couldcause in the course of optical sensing. This characteristic isparticularly advantageous when the body of the device, or at least ahousing portion thereof, is made at least in part of a transparentmaterial or material permeable to ambient light.

In various embodiments, such as the ones referred to in Claim 11, thedevice has a casing of its own, including the aforesaid body thatdefines the portion designed for propagation of optical radiation, aswell as a cover, which may advantageously integrate an electricalconnector. In embodiments of this type, the body of the device defines ahousing portion, housed in which at least in part is the optical moduleand, preferably, also a circuit support of the optical arrangement. Theabove housing portion may be defined integrally in the body of thedevice, as is for example specified in Claim 12, or else be at least inpart formed by a further body, for example the body of another device,such as a level sensor or a component for tanks of the a type known asUDM (Urea Delivery Module), or again a component comprising a heater ofthe liquid substance.

In various embodiments, then, the body or casing of the sensor devicemay be made up of a number of parts, using for the purpose differentmaterials deemed more convenient from the functional standpoint, asexplained hereinafter. For instance, in various embodiments, an opticalassembly including the emitter, the receiver, and a part of body throughwhich sensing optical radiation is to propagate, may be configured as apart distinct from another part of the body of the device, purposelyprovided with a through opening for installation of the aforesaidoptical assembly. In this way, the optical assembly may be easilypre-assembled, possibly tested, and then associated in a sealed way inthe corresponding assembly opening provided on the main body. In anembodiment of this type, the presence of a positioning element of thetype referred to in Claim 13, is advantageous in order to guaranteeproper positioning of the optical module.

The supporting and electrical-connection structure of the optical modulemay also consist of a single body provided with the aforementionedpositioning and/or blocking means, with the emitter and the receiverthat are associated to one and the same surface of said single body. Anembodiment of this type, for example as specified in Claim 14, isadvantageous in particular when the emitter and the receiver are inpositions set alongside one another, each facing a corresponding end ofan optical guide used for the purposes of detection of thecharacteristic of interest. The possible presence of lateral portionsset facing one another of a body of this sort may be advantageous forthe purposes of positioning the optical module and/or for support of anadditional emitter and an additional receiver, as explained hereinafter.

In embodiments in themselves autonomously inventive, such as the onesreferred to in Claim 15 and/or Claim 19, a sensor device is equippedwith an auxiliary optical arrangement, aimed at detecting possiblevariations of the characteristics of the plastic material through whicha sensing optical radiation is to propagate, these variations being, forexample, due to ageing and temperature variations. In this way, if needbe, it is possible to make a corresponding compensation of detectionsmade, for example, via the main optical arrangement, to the advantage ofreliability and precision of the device in the long term. According topreferential embodiments, the emitter and the receiver of the auxiliaryoptical arrangement can be integrated in the same optical module as theone that integrates the main emitter and receiver, or else be carried bya circuit board belonging to the level-sensing arrangement, to theadvantage of simplicity of assembly.

A sensor device according to a preferential embodiment, such as the onereferred to in Claim 17, enables use of a relatively simpleoptical-guide structure in order to obtain in any case an efficient andreliable propagation of sensing optical radiation, on the basis of theprinciples of inner reflection. Such a solution moreover renders lesscritical positioning of the emitter and of the receiver, which maysimply face the two ends of the optical guide. A sensor device accordingto a preferential embodiment, such as the one referred to in Claim 18,has instead an optical-sensing arrangement, operation of which is basedupon optical refraction, in particular in the passage of opticalradiation from a solid to a fluid, which enables a measurement with goodresolution.

BRIEF DESCRIPTION OF THE DRAWINGS

Further purposes, characteristics, and advantages of the presentinvention will emerge clearly from the ensuing detailed description,with reference to the annexed schematic drawings, which are providedpurely by way of non-limiting example and in which:

FIG. 1 is a sectioned perspective view of a generic container thatcomprises a sensor device according to possible embodiments of theinvention;

FIG. 2 is a partially sectioned perspective view of a sensor deviceaccording to possible embodiments of the invention;

FIGS. 3-4 are perspective views from different angles of a circuit of asensor device according to possible embodiments of the invention;

FIGS. 5-6 are exploded views, from different angles, of a sensor deviceaccording to possible embodiments of the invention;

FIGS. 7-9 are perspective views, from different angles, of an opticalmodule of a sensor device according to possible embodiments of theinvention;

FIG. 10 illustrates, with different perspective views, an emitter ofelectromagnetic radiation and a corresponding component, which can beused in a sensor device according to possible embodiments of theinvention;

FIG. 11 is a possible electrical diagram of an optical module of asensor device according to possible embodiments of the invention;

FIGS. 12-14 are perspective views of semi-finished products, which canbe used for production of an optical module of the type illustrated inFIGS. 7-9;

FIGS. 15-16 are perspective views of a mould, which can be used forproduction of an optical module of the type illustrated in FIGS. 7-9;

FIG. 17 is a partial perspective view of a circuit of a sensor deviceaccording to possible embodiments of the invention, with associated anoptical module of the type illustrated in FIGS. 7-9;

FIG. 18 is a perspective view aimed at representing a step of assemblyof a sensor device according to possible embodiments of the invention;

FIGS. 19 and 20 are a sectioned perspective view and a perspective viewof a portion of a sensor device according to possible embodiments of theinvention;

FIG. 21 is a vertical cross-sectional view of a sensor device accordingto possible embodiments of the invention;

FIGS. 22-26 are partial vertical cross-sectional views aimed atexemplifying operation of an optical sensor of a sensor device accordingto possible embodiments of the invention;

FIG. 27 is a simplified block diagram of an optical sensor of a sensordevice according to possible embodiments of the invention;

FIGS. 28-29 are exploded views, from different angles, of a sensordevice according to possible embodiments of the invention;

FIGS. 30-33 are perspective views aimed at representing some steps ofassembly of a sensor device according to possible embodiments of theinvention;

FIG. 34 is an exploded view of a sensor device according to possibleembodiments of the invention;

FIGS. 35-36 are perspective views from different angles of a protectiveelement, which can be used in a sensor device according to possibleembodiments of the invention;

FIGS. 37-38 are perspective views, from different angles, of an opticalmodule of a sensor device according to possible embodiments of theinvention;

FIGS. 39-43 are perspective views aimed at representing some steps ofassembly of a sensor device according to possible embodiments of theinvention;

FIGS. 44 and 45 are perspective views of an elastic element and of acorresponding blocking element, which can be used in a sensor deviceaccording to possible embodiments of the invention;

FIGS. 46-48 are partial perspective views aimed at representing somesteps of fixing of an elastic element of the type illustrated in FIG. 44by way of a blocking element of the type illustrated in FIG. 45;

FIGS. 49-50 are perspective views, from different angles, of an opticalmodule of a sensor device according to possible embodiments of theinvention;

FIG. 51 is a perspective view of an elastic element, which can be usedin a sensor device according to possible embodiments of the invention;

FIG. 52 is a partial perspective view aimed at representing a step ofassembly of a sensor device according to possible embodiments of theinvention;

FIGS. 53-57 are partial perspective views aimed at representing somesteps of fixing of an elastic element of the type illustrated in FIG.51;

FIGS. 58-59 are perspective views from different angles of a portion ofa sensor device according to possible embodiments of the invention;

FIG. 60 is a perspective view that shows a part of a sensor deviceaccording to possible embodiments of the invention;

FIG. 61 is an exploded view of a sensor device according to possibleembodiments of the invention;

FIGS. 62-63 are perspective views, from different angles, of an opticalmodule of a sensor device according to possible embodiments of theinvention;

FIG. 64 is a perspective view of a protective element, which can be usedin a sensor device according to possible embodiments of the invention;

FIGS. 65-69 are perspective views aimed at representing some steps offixing of a sensor device according to possible embodiments of theinvention;

FIG. 70 is a sectioned perspective view of a portion of a sensor deviceaccording to possible embodiments of the invention;

FIG. 71 is a vertical cross-sectional view of a sensor device accordingto possible embodiments of the invention;

FIG. 72 is a partially exploded view of a sensor device according topossible embodiments of the invention;

FIG. 73 is a partial exploded view of a sensor device according topossible embodiments of the invention;

FIGS. 74-75 are perspective views, from different angles, of an opticalassembly of a sensor device according to possible embodiments of theinvention;

FIG. 76 is an exploded view of an optical assembly of the typeillustrated in FIGS. 74-75;

FIG. 77 is a perspective view in partial section of a portion of asensor device according to possible embodiments of the invention;

FIG. 78 is a perspective view that shows a part of a sensor deviceaccording to possible embodiments of the invention;

FIG. 79 is a partial and schematic cross-sectional view of a portion ofa sensor device according to possible embodiments of the invention;

FIG. 80 is a detail at a larger scale of FIG. 79;

FIG. 81 is a partially exploded view of a part of a sensor deviceaccording to possible embodiments of the invention;

FIG. 82 is an exploded view of an optical module of a sensor deviceaccording to possible embodiments of the invention;

FIG. 83 is a partially exploded view of a part of a sensor deviceaccording to possible embodiments of the invention;

FIGS. 84-85 are perspective views aimed at representing some steps ofassembly of a sensor device according to possible embodiments of theinvention;

FIG. 86 is a vertical cross-sectional view of a sensor device accordingto possible embodiments of the invention;

FIGS. 87-88 are partial vertical cross-sectional views aimed atexemplifying operation of an optical sensor of a sensor device accordingto possible embodiments of the invention;

FIGS. 89-90 are partially exploded views, from different angles, of asensor device according to possible embodiments of the invention;

FIG. 91 is an exploded view of an optical module of a sensor deviceaccording to possible embodiments of the invention;

FIGS. 92-93 are perspective views from different angles of an opticalmodule of a sensor device according to possible embodiments of theinvention;

FIGS. 94-95 are perspective views aimed at representing some steps ofassembly of a sensor device according to possible embodiments of theinvention;

FIGS. 96-97 are vertical cross-sectional views, according to twodifferent parallel axes of section, of a sensor device according topossible embodiments of the invention;

FIG. 98 is an electrical diagram of an optical module, which can be usedin sensor device according to possible embodiments of the invention;

FIG. 99 is a simplified block diagram of an optical sensor of a sensordevice according to possible embodiments of the invention;

FIGS. 100-101 are partially exploded views, from different angles, of asensor device according to possible embodiments of the invention;

FIGS. 102-103 are perspective views, from different angles, of anoptical element of a sensor device according to possible embodiments ofthe invention;

FIG. 104 is a partial exploded perspective view of a circuit of a sensordevice according to possible embodiments of the invention, with acorresponding optical module;

FIGS. 105-108 are perspective views aimed at representing some steps ofassembly of a sensor device according to possible embodiments of theinvention;

FIG. 109 is a vertical cross-sectional view of a sensor device accordingto possible embodiments of the invention;

FIG. 110 is a horizontal cross-sectional view of the sensor device ofFIG. 109;

FIG. 111 is a vertical cross-sectional view of the sensor device ofFIGS. 109-110, according to a plane of section orthogonal to that ofFIG. 109;

FIG. 112 is a schematic perspective view of an electrical-connectionelement, in the form of flexible printed-circuit board, which can beused for producing optical modules according to embodiments of theinvention;

FIGS. 113 and 114 are schematic perspective views from different anglesof a supporting and electrical-connection structure integrating anelement of the type represented in FIG. 112;

FIGS. 115 and 116 are schematic perspective views from different anglesof an optical module that can be used in a sensor device according topossible embodiments of the invention, in two different conditions;

FIGS. 117 and 118 are partially exploded schematic views of a supportingand electrical-connection structure of an optical module that can beused in a sensor device according to possible embodiments of theinvention; and

FIG. 119 is a schematic perspective view of an optical module includingthe structure of FIGS. 117-118.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Reference to “an embodiment” or “one embodiment” in the framework of thepresent description is intended to indicate that a particularconfiguration, structure, or characteristic described in relation to theembodiment is comprised in at least one embodiment. Hence, phrases suchas “in an embodiment”, “in one embodiment, “in various embodiments”, andthe like, that may be present in different points of this description,do not necessarily refer to one and the same embodiment. Furthermore,particular conformations, structures, or characteristics defined in theframework of the present description may be combined in any adequate wayin one or more embodiments, that may eve differ from the onesrepresented. The reference numbers and spatial references (such as“upper”, “lower” “top”, “bottom”, etc.) used herein are merely forconvenience and hence do not define the sphere of protection or thescope of the embodiments. It should be considered, for example, that,for needs of greater clarity, in various attached figures the deviceforming the subject of the invention is represented in a conditionturned upside down with respect to that of normal operation. It ispointed out that, in the present description and in the attached claims,the adjective “outer” or “external”—when referred to a surface of atleast part of an (interface) wall of a body of the device describedherein—is intended to designate a surface designed to face the inside ofa generic container or of a duct, i.e., in contact with the liquidsubstance undergoing detection, whereas the adjective “inner” or“internal” is intended to designate an opposite surface of the aforesaidwall, i.e., a surface designed to be located on the outside of the tankor duct, and in any case not in contact with the substance. It islikewise pointed out that, in the present description and in theattached claims, by “optical radiation” is meant that part of theelectromagnetic spectrum that comprises radiation in the range between100 nm (nanometres) and 1 mm (millimetre), including ultravioletradiation (100 to 400 nm), visible radiation (380-780 nm), and infraredradiation (780 nm to 1 mm). Moreover being understood as comprised inthe scope of the invention are both sources of optical radiation of a“coherent” or laser type and sources of optical radiation of a“non-coherent” type. Furthermore, where not otherwise specified orevident from the context described, the term “material”, for examplewhen referred to the body of an element that has been described, it isto be understood as indicating a single material (e.g., a metal or aplastic material) or a composition of a number of materials (e.g., ametal alloy, or a composite material, or a mixture of materials, etc.).

In FIG. 1, designated as a whole by 1 is a generic container, such as atank, in particular a tank of a motor vehicle. In the sequel of thepresent description, it is to be assumed that this container 1 (alsodefined hereinafter for simplicity as “tank”) is designed to contain aliquid additive, or reducing agent, and forms part of an exhaust-gastreatment system of an internal-combustion engine, represented as awhole by the block 2. In various embodiments, the treatment system 2 isof an SCR type, as explained in the introductory part of the presentdescription, used for abatement of nitrogen-oxide emissions, for examplein motor vehicles, in particular with diesel engines. The aforesaidreducing agent is hence preferably a liquid solution, in particular ureain a solution of distilled water, such as the one known commercially bythe name AdBlue™. The container 1 could in any case be replaced by aduct of a hydraulic system and/or be used for other purposes and/or insectors different from the automotive sector, and could be designed tocontain a different liquid or fluid substance of some other type thatcan be detected optically (the definitions provided hereinafteroccasionally referred to a liquid substance or to a reducing agent mayhence be understood with reference to a different liquid or fluidsubstance). The main body 1 a of the tank 1 may be made of any material,preferably a material that is chemically resistant to the liquidsubstance or solution and is, preferably, electrically insulating, forexample a suitable plastic material, according to known technique, suchas a high-density polyethylene (HDPE). There may possibly be associatedto the tank 1 a heater of a type in itself known, used for heating thetank itself and/or its contents, for example in the case of freezing. Anelectric heater is represented schematically in the figures by the blockdesignated by EH. Advantageously, in various embodiments, such a heaterEH is associated to or integrated in the sensor device according to thepresent invention.

In the schematic example illustrated, the tank has an upper part 3, forexample an upper wall thereof, at which is an opening 3 a for topping upthe liquid solution. A lower part 4 of the tank 1, for example its lowerwall, then has an outlet opening 5, via which the solution comes out oris drawn in, for example via a pump, for supplying the liquid to thesystem 2. Once again at the lower part 4, the tank 1 has a secondopening, designated by 6, where a body of a sensor device according tovarious possible embodiments of the invention is fixed in a sealed way.In preferred applications, in fact, the sensor device forming thesubject of the invention is designed to be installed in the lower partof a container or of a duct, so that an outer surface of its body is atleast in part in contact with the liquid substance, even when this is ata minimum level.

In various embodiments, a body of the sensor device according to theinvention defines itself at least part of the outlet opening of the tank1, with the latter that could hence be provided with just one opening 6,instead of the openings 5 and 6.

The sensor device, designated as a whole by 10, includes a housingand/or assembly part 12, configured for being coupled in a sealed way tothe opening 6. The part 12 in any case has a closing or bottom structureincluding at least one wall (designated hereinafter by 21), which isdesigned to come into contact with the liquid solution contained in thetank 1. As will be seen, in accordance with the invention, the sensordevice 10 comprises at least one detection arrangement, in particular ofan optical type, for detection of one or more characteristics of theliquid substance or solution contained in the tank 1: for this purpose,the sensor device 10 includes a detection part (also defined hereinafteras “optical positioning site”) which in various embodiments may also beconfigured as projecting towards the inside of the tank 1.

It should be noted that, instead of being directly mounted at theopening 6 of the tank 1, the device 10 according to the invention mayenvisage, or be associated to, or integrated in, a component that ismounted in a sealed way at a different opening of the tank itself, forexample defined in a component of the type commonly known as UDM (see,for example, WO 2008/138960 A). Components of this type typicallyinclude other functional devices and/or a passageway for intake of thereducing agent from the tank, to the passageway there being in generalconnected the intake of the pump for the drawing in the agent itselffrom the tank. In any case, as will be seen, in preferred embodiments,the casing body of the device 10, and in particular at least its housingportion 12, is designed to extend prevalently on the outside of thecontainer or duct in which the liquid substance is located, except forat least a portion of a wall thereof, associated to which is the opticaldetection arrangement. In other words, then, preferentially, the casingbody of the sensor device forming the subject of the invention is notdesigned to be completely or prevalently positioned within a volume forcontaining the liquid substance, nor to be completely or prevalentlyimmersed in the latter.

In FIG. 2 a device 10 according to one embodiment is represented inisolation. The device 10 has a device body 10 a that defines the housingand/or assembly portion 12, which is preferably provided with a closingcover 13.

Preferably, the body 10 a is hollow for housing at least part of thecomponents of an arrangement for detection of one or morecharacteristics of the substance contained in the tank 1, in particulara sensor of an optical type, preferably of an opto-electronic type,suitable for detection of the quality of the aforesaid substance (inwhat follows, for simplicity, reference will hence also be made only todetection of the quality of the substance).

In various embodiments, the body 10 a, or at least one part of itsportion that is to come into contact with the liquid solution, is madeof a mouldable thermoplastic material, such as a polypropylene (PP) or ahigh-density polyethylene (HDPE), or a polysulphone (PSU). Practicaltests conducted by the present Applicant have on the other hand made itpossible to ascertain that a material that is particularly suitable—alsoin view of the particular modalities of detection of quality describedhereinafter—is a cyclic-olefin copolymer (COC).

Materials of this type—which are used also in the medical field—presentparticularly advantageous characteristics for the application consideredherein, amongst which are to be emphasized the low density, the very lowwater absorption, the excellent barrier properties to water vapour, thehigh stiffness, strength, and hardness, the high resistance to extremetemperatures and to thermal shock, the excellent resistance toaggressive agents such as acids and alkalis, the excellent properties ofelectrical insulation, the ease of manageability using ordinary methodsof treatment of thermoplastic materials, such as injection moulding,extrusion, blow moulding, and injection blow moulding.

Once again in FIG. 2 it may be noted how the housing part 12 defines acavity, designated as a whole by H, which together with the cover 13delimits a housing for at least part of the electrical and electronicsensing components. In a preferred embodiment, at least part of thesecomponents is mounted on an electrically insulating substrate 15 thatprovides a circuit support or PCB (Printed Circuit Board), also definedhereinafter as “circuit”, given that mounted and connected thereon areelectrical and/or electronic components. The circuit support 15 ispreferably made of a material suitable for production of printedcircuits, such as FR4 or a similar composite material such asfibreglass, or again a ceramic material or a polymer-based material,preferably a mouldable material for the purposes of production of thecircuit support 15.

With reference also to FIGS. 3 and 4, associated to the circuit support15 are prevalently the sensing and/or control electronic components ofthe device 10, which are connected to the optical sensor. The aforesaidcomponents preferentially include components for treatment andprocessing of signals of detection of at least one characteristic of thesubstance, such as its quality.

Preferably associated to the circuit support 15 are moreovercorresponding terminals for external electrical connection of the device10, preferably of a generally flat shape, visible, for example, in FIGS.5 and 6, where they are designated by 16. These terminals 16 form, witha connector body 13 a of the cover 13, an interface or connector forexternal electrical connection of the device 10, for example to acontrol unit of the system 2 on board the vehicle.

In the example illustrated a single circuit support 15 is provided, butin possible variant embodiments a number of circuit supports may beprovided connected together by means of suitableelectrical-interconnection means and possibly mechanical-interconnectionmeans, for example a circuit support including firstelectrical/electronic components and a circuit support including secondelectrical/electronic components, with electrical conductors orconnectors for electrically connecting together conductive paths of thetwo supports, or again a circuit support carrying part of the componentsjust for detection of quality (or other characteristic quantity of thesubstance), connected to a circuit support carrying at least part of thecomponents for detection of a different quantity, for example atemperature.

Once again with reference to FIGS. 3 and 4, in various embodiments thecircuit support 15, preferably having a generally flat shape, hasassociated on one of its major faces—herein conventionally defined as“back”—a control circuit arrangement, designated as a whole by 17,preferentially comprising an electronic controller MP, for example amicroprocessor or a microcontroller.

The controller MP preferably comprises at least one processing and/orcontrol logic unit, a memory circuit, and inputs and outputs, amongstwhich inputs of an analog/digital type. The arrangement 17 or thecontroller MP then comprises elements for conditioning and/or treatmentof the signals for detection of quality of the liquid solution. Itshould be noted that the components associated to the circuit support 15or the arrangement 17, except for its connection elements 16 and 53, arerepresented only in FIGS. 3-4, for needs of clarity of the subsequentdrawings. The components of the circuit arrangement 17 are connected toelectrically conductive paths provided on the circuit support, notindicated.

In various embodiments, the device according to the invention comprisesat least one temperature sensor, for detection of at least one of atemperature of the liquid solution and an ambient temperature, such asthe temperature of the air within the cavity H. Preferentially, at leastone temperature sensor is provided on the circuit support 15. Atemperature sensor, for example of an NTC type, may be mounted on thecircuit support 15 so as to be substantially in contact with the innerside of a wall of interface with the liquid substance (such as the walldesignated hereinafter by 21), as represented schematically by thetemperature sensor 19 a of FIG. 4. Also represented schematically in theexample shown is a second temperature sensor 19 b. Assuming an assemblyof the device 10 in the tank 1 of the type illustrated in FIG. 1, thetemperature sensor 19 a can be used for detecting the temperature of theliquid, whereas the sensor 19 b can be used for detecting thetemperature that exists in the cavity H, for example in order tocompensate variations or thermal drifts of the opto-electroniccomponents and/or of the electronic components of the control circuit,in particular in order to improve the measurements made by the device.

In various embodiments, such as the one exemplified herein, themeasurement made by the at least one temperature sensor provided in thedevice is an indirect measurement, given that the temperature sensor isnot directly in contact with the liquid substance. It will in fact beappreciated that, in various embodiments, the at least one temperaturesensor 19 a is housed within the body 10 a of the device (and especiallywithin its portion 12), and hence not directly in contact with theliquid substance present in the tank 1, thus detecting at least onetemperature on the outside of the body 10 a. For this purpose, invarious embodiments, the control circuit arrangement 17 of the device 10is provided—in a way in itself known—for making an appropriatecompensation of the measurement made by the temperature sensor 19 a,which takes into account at least the presence of a wall (here the walldesignated hereinafter by 21) set between the temperature sensor and thesubstance (e.g., in a memory of the circuit arrangement 17 there may becontained corresponding corrective parameters, based upon experimentalanalyses).

In various embodiments, such as the one exemplified herein, themeasurement made by the at least one temperature sensor provided in thedevice is a direct measurement, given that the temperature sensordetects directly the ambient temperature or that of the air in contactwith other components of the device, for example in the case of thetemperature sensor 19 b that detects the ambient temperature within thecasing of the device 10 in which it is located, such as the casing heredefined by the parts 10 a and 13. It will in fact be appreciated that,in various embodiments, at least one temperature sensor can be housedwithin the casing of the device and designed to detect at least onetemperature within the casing itself.

In various embodiments, a measurement made by two temperature sensors isenvisaged, both of which are located within the casing of the device,preferably a direct measurement and an indirect measurement of thetemperature, respectively for a measurement of the temperature frominside and from outside the casing itself.

In various embodiments, at least one temperature sensor, for example oneor more of the ones referred to above, is provided in the device 10 forcompensating the value of detections made via the quality sensor.

In various embodiments, such as the one exemplified, all the sensors, inparticular the quality and temperature sensors are isolated from theliquid substance, preferably via at least one wall of the body of thedevice.

As may be seen in FIGS. 5 and 6, in various embodiments the housingand/or assembly part 12 includes a peripheral wall 20 and a bottomstructure or wall 21, which define the cavity H designed for housing atleast part of the electrical and/or electronic components of the device10. Preferably, the peripheral wall 20—here of a substantiallycylindrical shape—has a flange 20 a defining a corresponding seat 20 b,in particular a circumferential seat, for fixing in position and/or forsealing the cover 13. In the mounted condition, i.e., where the device10 is assembled, at least one part of the bottom structure or wall21—and in particular its outer side—is to come into contact with theliquid solution contained in the tank: for this reason, the wall 21 willalso be defined as “interface wall”. As may be noted in particular inFIG. 5, in various preferred embodiments, at least one of the wall 20and the wall 21 defines/define, at its/their inner side, formations orseats for positioning of the circuit support 15 within the cavity H,preferably but not necessarily a substantially vertical positioning.Preferentially, in the cavity H at least two formations or seats 22 areprovided for the purpose, in substantially opposite positions.

From FIGS. 5-6 it may be appreciated how, in preferential embodiments,the cover 13 also performs functions of electrical connection in so faras it includes or defines a generally hollow connector casing 13 a, forhousing the electrical terminals 16 and, possibly, at least part of thecircuit 15 and/or of the optical sensor. In the example, the connectorcasing 13 a projects in an axial direction of the cover 13 or of thesensor device 10 (in FIGS. 1 and 2, the main axis of the device isdesignated by X), but other orientations are of course possible, forexample orthogonal or angled with respect to the aforesaid axis. Thecover 13 is designed for being fixed on the main body 10 a, inparticular on its housing and assembly part 12, so as to close thecavity H, preferably in a sealed way.

In various embodiments, the cover 13 defines for the purpose a flange 13b, for fixing the part 12 to the flange 20 a, for example via gluing orwelding (in particular of a laser or vibration type or via remelting ofat least part of the perimeter of the flange 13 b and 20 a made ofplastic material), or else via some other mechanical fixing between theabove flanges, such as a thread or a bayonet coupling, possibly withinterposition of sealing means, such as an elastic gasket. In theexample of FIGS. 5 and 6, the flange 13 b of the cover 13 defines anannular projection 13 b ₁, designed for coupling in the seat 20 b of theflange 20 a of the body 10 a (see also FIG. 21), Preferably, provided inat least one of the bodies 10 a and 13 are means for fixing the device10 to the tank, such as perimetral holes, for example holes 13 d in oneor more radial formations 13 c of the flange 13 b (see, for example,FIG. 5).

In the assembled condition of the device 10, the terminals 16 aredesigned to project within the connector casing 13 a of the cover 13.For this purpose, the cover 13 has corresponding passages for theseterminals, designated by 13 e in FIG. 6; alternatively, the terminals 16could be overmoulded with the plastic material of the cover 13. FromFIG. 6 it may be noted how, in various embodiments, within the cover 13,which also defines a corresponding cavity, positioning formations orseats 13 f are defined for the circuit support 15, preferably inpositions homologous to the formations or seats 22 of the body 10 a.

In accordance with the invention, as has been said, the sensor device 10includes at least one optical arrangement for detection of quality (orother characteristic/characteristics) of the substance being checked,and possibly an arrangement for detecting a temperature, wherepreferably these sensing arrangements comprise parts in common of thedevice 10. These parts in common may be of a basically mechanical type,such as a single body, for instance the one designated by 10 a, or elsea number of bodies coupled together, for example welded or glued orengaged together, or again a number of bodies fitted or slotted at leastin part into one another. In addition and/or as an alternative, theparts in common may be of an electrical and/or electronic type, andinclude, for example, a circuit board (such as the one designated by15), a connector (such as the connector 13 a, 16), one or more controlcircuit components (such as the controller MP).

In embodiments in which both the quality sensor and at least one sensorfor detecting another quantity, such as the temperature sensor, areprovided, the device according to the invention, and in particular itscontrol electronics, is prearranged for transmitting both firstinformation representing the quality of the substance and secondinformation representing the at least one other characteristic, such asa value of temperature, by means of an electrical connector and/or bymeans of electrical terminals in common to the two (or three) sensingarrangements. In various embodiments, both the first information and thesecond information are transmitted via one and the same signal,preferably one and the same serial signal containing a plurality of dataor values, such as data or values in digital format or encoded accordingto a predefined protocol. For this purpose, the control electronics ofthe device is preferably pre-arranged for transmission of data,preferably in the aforesaid serial format, very preferably by way of aserial interface and/or protocol, such as a SENT (Single Edge NibbleTransmission) protocol or CAN (Controller Area Network) protocol.

In preferred embodiments, the quality-sensing arrangement according tothe invention comprises at least one emitter of optical radiation and atleast one receiver of optical radiation, and a part of the sensor device10, i.e., of its body 10 a, is configured so as to contribute topropagation of optical radiation from the emitter to the receiver. Inwhat follows, for simplicity it will be assumed that the aforesaidoptical radiation is in the visible, there, however, being possible adifferent frequency of optical radiation for the purposes ofimplementation of the invention: hence, in what follows, reference willbe made to rays or beams of visible light. Consequently, for simplicity,in what follows, the sensor for detecting quality or othercharacteristic/characteristics will also be defined as “optical sensor”.

For this purpose, in various embodiments, the wall 21 that delimits thecavity H of the housing part 12 at the bottom is made at least in partof a material designed for propagation of light, at least by refractionand/or reflection, and at the aforesaid part there are operativelyassociated the emitter and the receiver. This material is preferably atransparent material, for example selected from cyclic-olefin copolymers(COCs), or a polysulphone (PSU), or a polypropylene (PP), or ahigh-density polyethylene (HDPE).

In various embodiments, at least one part of the wall 21 is shaped todefine an optical site for positioning the aforesaid emitter andreceiver.

In various preferred embodiments, the emitter and receiver form part ofone and the same optical module, which is mounted at the aforesaidoptical positioning site. With reference to FIG. 5, an aforesaid site isdesignated as a whole by 30, while an aforesaid module is designated asa whole by 40 in FIG. 2. As will emerge hereinafter, in variousembodiments, the optical positioning site comprises a particularconformation of the wall 21 or else of a part thereof designed forpropagation of the light beam. In preferred embodiments, the opticalsite 30 provides the previously mentioned second sensing part of thedevice 10, belonging to the optical sensor, which in various embodimentsis designed to project at least in part towards the inside of the tank1.

Visible in FIGS. 7-9 is an optical module obtained according to possibleembodiments of the invention. The module 40 has a supporting andelectrical-connection structure 41 (see also FIGS. 5 and 6), made inpart of electrically insulating material and in part of electricallyconductive material. The structure 41 of the module is pre-arranged formounting of a light emitter 42 (only partially visible in FIG. 8, in sofar as it is covered by a corresponding space filter 43, describedhereinafter, but visible in FIGS. 5-6) and at least one light receiver44. In preferred embodiments of the invention, the emitter is anon-diffused lambertian light source, for example a suitable LED(light-emitting diode). According to preferred embodiments of theinvention, the light receiver 44 comprises two distinct receivers,designated by 44 a and 44 b, for example photodetectors or photo-diodessuitable for detecting the light emission generated by the emitter 42.

In various embodiments, the emitter 42 and the receiver 44 have theirrespective active parts for emission and reception, respectively, thatgenerally face one another, but are arranged angled with respect to oneanother, preferably in such a way that their respective axes intersect.With reference, for example, to FIG. 22, the emitter 42 and the receiver44 are arranged according to respective planes of lie 42 _(x), 44 _(x)that form between them an angle c that is less than 90°. Instead, thetwo planes passing through the axes 42 _(y), 44 _(y) of the receiver andof the emitter, respectively (meaning thereby two planes orthogonal tothe axis of the sheet of FIG. 22), form between them an angle greaterthan 90°. In general, then, the axes 42 _(y), 44 _(y) of the receiverand of the emitter are inclined with respect to the main axis X of thedevice 10 (see FIGS. 1 and 2).

The angle α is predefined on the basis of the plastic material used forthe interface wall (i.e., a wall of the body 10 a, here the wall 21, inparticular in a position substantially corresponding to the positioningsite 30), the type of optical radiation (i.e., the type of emitter 42)that it is intended to adopt, and the type of fluid that is to bemeasured.

Preferably, with the use of certain plastic materials, the angle αand/or the angle of incidence of the ray emitted by the emitter withrespect to the interface surface, namely, the critical angle, iscomprised between 50° and 70°. For instance, for measurement of thequality of urea in aqueous solution using as plastic material COC,considering a light emission with a wavelength equal or close to 630 nm,the angle α must preferably be comprised between 52° and 54°, inparticular 53°. Alternatively, in the same application and using asplastic material for the interface wall PSU, the angle α must preferablybe comprised between 63° and 65°, in particular 64°. However, in asimilar configuration, an appropriate angle α may be predefined forother materials of the interface wall, such as a PP or a HDPE.Alternatively, there may be envisaged a source of light emission of aninfrared type, for example with wavelength equal or close to 850 nm or860 nm, envisaging an appropriate angle α, also taking into account thematerial of the interface wall, such as a COC plastic material, or aPSU, or a PP, or a HDPE. The emitter and the receiver (or its individualphotodetectors) must be positioned with their axes 42 _(y) and 44 _(y)orthogonal to the optical surfaces so that the ray R1 will impinge onthe surface 21 ₁ with an angle (with respect to the vertical or withrespect to an axis parallel to the axis X or to an axis perpendicular tothe surface 21 ₁) equal to the critical angle: with reference to theprevious examples, with COC and urea solution the aforesaid angle willpreferably be comprised between 62° and 66°, in particular 64°, and withPSU and urea solution the angle will preferably be comprised between 56°and 60°, in particular 58°.

In various other embodiments, on the other hand, the emitter and thereceiver may be arranged in some other way, for example with theirrespective axes 42 _(y), 44 _(y) generally parallel (as, for example, inthe embodiments of FIGS. 81-88, 89-99, 100-111).

In preferred embodiments, the structure 41 includes a plurality ofbodies made of insulating material, which are connected together bymeans of electrically conductive elements at least in part elasticallydeformable. Preferentially, the structure 41 includeselectrical-connection terminals, which are also at least in partelastically deformable.

In the case exemplified in FIGS. 7-9, the structure 41 comprises a mainbody 45, in a central position, basically performing centring and fixingfunctions, and two lateral supporting bodies 46 and 47, these bodiesbeing preferably made of plastic or thermoplastic material, or of amouldable resin.

As may be seen in particular in FIG. 7, at two opposite peripheral sidesof the central body 45 there project mechanical and electricalconnection elements 48 and 49, preferably constituted by elasticallyflexible or deformable metal conductors, associated to which are thesupporting bodies 46 and 47, respectively. In a position correspondingto another peripheral side of the body 45 there project, instead,electrical-connection terminals 50, which are also preferablyconstituted by elastically flexible metal conductors. The terminals 50are used for electrical connection of the module 40 to the controlelectronics of the device, in particular to the circuit support 15,whereas the conductors 48 and 49 are exploited for electrical connectionof the emitter 42 and of the receiver 44, i.e., of its detectors 44 aand 44 b. As will be seen, the conductors 48, 49 and the terminals 50are prearranged so as to render elastic or deformable the correspondingmechanical and/or electrical connection, in order to guarantee theprecise relative positioning between parts of the device, as well ascompensating possible dimensional and/or positioning tolerances toprevent damage caused by assembly and/or by vibrations during operation.

In various embodiments, defined at the upper face of the central body 45is a first formation 51 for centring and/or blocking, which preferablyhas a substantially cylindrical shape provided with a transverse cut,not indicated. As will be seen, this upper formation 51 is configuredfor contributing to centring and/or blocking of a blocking and/orpositioning element, designated by 60 in FIGS. 5 and 6, describedhereinafter. Preferentially, the formation 51 is moreover hollow inorder to contribute to centring of the module 40 with respect to thecorresponding positioning site 30. In preferred embodiments, the body 45is traversed by two through openings 51 a, which open substantially attwo diametrally opposite parts of the formation 51, in particular at therespective ends of the aforesaid transverse cut.

In various embodiments, at the bottom face of the central body 45 isdefined a second formation 52, which is also designed to providefunctions of centring or positioning of the module 40 with respect tothe site 30 in order to guarantee proper positioning of the emitter 42and of the receiver 44 with respect to optical surfaces provided at thesite 30. For this purpose, as will be seen, a contribution is providedby the elasticity or the at least partial elastic deformability of theconductors 48 and 49. In preferred embodiments, the formation 52 or partof the body 45 also performs functions of optical shield, as describedhereinafter.

The formation 52 includes at least one projecting wall 52 a, whichextends in a direction generally orthogonal to at least part of theconductors 48 and 49, such as a part on which the body 45 isovermoulded.

Preferably, at the two longitudinal ends of the wall 52 a two furtherprojecting walls 52 b are provided, transverse to the wall 52 a: hence,in these embodiments, the formation 52 substantially has an H-shapedprofile in plan view, including a projecting wall. At the ends of thewalls 52 b there may possibly be provided further small walls orreinforcement ribbings, as illustrated.

As may be noted in particular from FIGS. 8 and 9, the two throughopenings 51 a open, at the bottom face of the body 45, on the two sidesof the wall 52 a.

The two lateral bodies 46 and 47 each have, on their corresponding upperface, a groove 46 a, 47 a, designed for providing the seat for twoopposite arms of the aforementioned blocking and/or positioning element60, which is preferentially an elastic element. The shape of the groovesor seats 46 a, 47 a is such as to prevent movement of the aforesaid armsand guarantee adequate pressure of the module 40 and/or of the twolateral bodies 46 and 47 against corresponding contrast means, such as aformation forming part of the site 30 or belonging to the wall 21.

Preferably, associated to the module 40 or to at least one of the bodies46 and 47 is at least one positioning and/or anti-rotation element: forthis purpose, in various embodiments, the bodies 46 and 47 each have atleast one lower appendage or projection 46 b and 47 b, for exampleshaped like a tooth, at their lower peripheral edge, which is designedto couple with an appropriate positioning seat of the site 30 or of thewall 21; alternatively, the aforesaid positioning and/or anti-rotationelements could be in the form of seats, designed to couple with anappropriate projection or a positioning tooth of the site 30 or of thewall 21.

Provided at the lower face of the bodies 46 and 47 are the ends of therespective conductors 48 and 49, for connection of the emitter 42 and ofthe two photodetectors 44 a and 44 b that constitute the receiver 44.The electrical connection of the aforesaid electronic components to theconductors 48 and 49 may be made using standard techniques employed inthe sector of electronic circuits, for example welding/reflow.

The conductors 48 and 49 have an intermediate portion that is bent, hereat an obtuse angle, in such a way that the bodies themselves, and hencethe emitter on the one hand and the receiver on the other, are inpositions angled with respect to one another and with respect to thebody 45. Also the terminals 50 have an intermediate portion that isbent, here with a substantially U-shaped (or alternatively, S-shaped orZ-shaped) bend, to enable elastic assembly as mentioned previously.

In various embodiments, associated to the emitter 42 is an opticalfilter or space filter 43, in particular in order to select orconcentrate the light beam. An example of such a filter is illustratedin FIG. 10, in different views, together with the emitter 42. The spacefilter 43 is basically a component made of plastic material notpermeable to optical radiation or light, in particular moulded,preferably mounted directly on the emitter 42; alternatively, the spacefilter 43 could be mounted or fixed to the body 46.

The filter 43 is preferably configured as a cap provided with an opening43 a in a wall thereof opposite to the light source 42 a of the emitteritself. This opening, which in FIG. 10 is substantially in the form of acircular hole, filters and selects or concentrates the light beamemitted by the emitter itself. The body of the filter 43 is preferablymounted with interference fit or engaged on the electronic componentthat provides the emitter 42. For this purpose, preferentially, providedon the inner side of at least two opposite walls of the body of thefilter 43 are centring and/or fixing internal ribbings or reliefs 43 b.Instead of a hole, the filter may be provided with an opening having adifferent shape designed for the purpose, such as a slit (asillustrated, for example, in FIG. 38) or else an oval or substantiallysquare shape, the hole possibly having a shape with variable section.

Represented by way of example in FIG. 11 is a possible electricaldiagram of the module 40, for its connection to a correspondinginterface circuit, here represented by the circuit arrangement 17 of thecircuit support 15 (see FIG. 4). As may be noted, the terminals 50preferably make it possible to have as input and output signals a supplylevel Vcc of the emitter 42, a ground GND, and two voltage signals A andB for the two photodetectors 44 a and 44 b. These signals A and B reachthe circuit arrangement 17, preferably for a numeric processing by thecontroller MP (as also represented schematically in FIG. 27).

In preferred embodiments, the bodies 45, 46, and 47 of the module areelements overmoulded on the conductors 48, 49 and on the terminals 50.For this purpose, in various embodiments, obtained from a substantiallyflat metal strap is a first semi-finished product SM1 visible in FIG.12. The aforesaid strap may, for example, be made of copper or brass orsome other conductive metal, preferably coated at least in part with ametal material designed to facilitate soldering of the emitter component42 and receiver component 44 and/or of the circuit support 15 (such asgold or tin).

The semi-finished product SM1, which can be obtained, for example, viablanking from the aforesaid strap, defines in a single piece a planeshape of the conductors 48, 49 and of the terminals 50, which are joinedtogether by means of accessory parts, some of which are designated by49′ and 50′. Moulded on the semi-finished product SM1 are the bodies45-47, thereby obtaining a second semi-finished product, designated bySM2 in FIG. 13. From the second semi-finished product SM2 the aforesaidaccessory parts are then eliminated, for example via blanking, so as todefine the conductors 48, 49 and the terminals, once again having aplane configuration, as is clearly visible in FIG. 14. Next,preferentially, the intermediate portions of conductors and terminalsare bent, as explained above, to assume the configuration visible inFIGS. 7-9. FIGS. 15 and 16 exemplify a mould, which can be used forformation of the semi-finished product, the two parts HM1 and HM2 ofwhich include respective impressions HM1 ₁ and HM2 ₁, designed forpositioning of the original semi-finished product SM1 of FIG. 12 and fordefinition of the profiles of the bodies 45-47 that are to beovermoulded on the aforesaid semi-finished product.

In other embodiments, a number of bodies of an optical module, such asthe bodies 45-47, may be elements overmoulded at least in part on aflexible printed circuit board, which comprises or integrates at leastpart of the conductors (such as the conductors 48, 49) and terminals(such as the terminals 50). Alternatively, one or more bodies of amodule, such as the bodies 45-47, may be elements moulded separately, inparticular made of polymeric material, and subsequently associated, forexample via gluing, to conductors (such as the conductors 48, 49) andterminals (such as the terminals 50) or to a flexible printed circuitboard comprising at least in part the aforesaid conductors andterminals. For this purpose, a number of bodies of an optical module,such as the bodies 45-47, may also be joined together by respectiveflexible or articulated body portions, or else may be obtained as asingle body comprising the aforesaid bodies joined by body portions ofsmall thickness. In further embodiments, the bodies of an optical modulemay be moulded elements comprising an insulating polymer, whereas thecorresponding conductors and/or terminals may be moulded elements madeof an electrically conductive material that comprises a polymer, whichare preferably comoulded or overmoulded on one another.

According to an inventive aspect, a number of bodies of an opticalmodule, such as the bodies 45-47, are positioning and/or fixing mouldedelements that can vary at least in part their relative position duringassembly of the module. In particular, in various embodiments, thesebodies, such as the bodies 45-47, are able to vary a respective relativeangle, this variation being allowed also by a flexibility ofcorresponding conductors (such as the conductors 48, 49) and/orterminals (such as the terminals 50).

As has been explained, in various embodiments, the optical module 40 isconnected in electrical-signal communication to the electronics of thesensor device 10, in particular to the circuit arrangement 17 of thecircuit support 15. In various embodiments, for this purpose the circuitsupport 15 has suitable connection elements, for electrical connectionof the terminals 50 of the module 40. These connection elements may forexample be in the form of one or more from among metallized holes,solder pads, connectors provided with holes and small pins, at which thefree ends of the terminals 50 are, for example, soldered or electricallyconnected, as represented schematically in FIG. 17, where the aforesaidholes are designated by 53 (see also FIGS. 4-5). In the example, theholes 53 (or the different connection means that replace them) are in agenerally central position of the circuit support 15; this must not,however, be deemed essential. As may be appreciated from FIG. 17, thebent portion of the terminals 50 is elastically flexible or deformable,thereby enabling performance of a function of spring, which enablesautonomous adaptation of the relative position between the module 40 andthe circuit support 15.

Represented in FIG. 18 is a step of insertion of the circuit support 15,with the associated optical module 40, within the body 10 a of thedevice 10. Visible in this figure is a possible embodiment of thepositioning site 30 for the module 40.

The site 30 includes at least one projecting element or formation 31that rises, preferentially in an orthogonal direction, from the innerside of the wall 21 of the housing part 10 a, designed to performsubstantially functions of optical prism. The formation 31 basicallyconsists of a wall—here substantially perpendicular to the inner side ofthe wall 21—which is made of the same material as the wall 21, inparticular a transparent material or material permeable to the light oroptical radiation used by the optical module 40, and that is preferablydivided, by an intermediate cut or cavity 32, into two upright parts 33and 34. The upright parts 33 and 34 are substantially specular to oneanother and each define an inclined face or surface 33 a and 34 a, in alateral position, or in a position external to the intermediate cavity32. In the case exemplified, the upright parts each have anapproximately triangular shape, in particular the shape of aright-angled triangle, the hypotenuses of which forms the aforesaidopposite inclined surfaces.

Rising from the two upright parts 33 and 34, in the proximity of theirupper ends, are positioning appendages 35 generally parallel to oneanother, preferably having a cross section substantially complementaryto that of the through openings 51 a of the central body 45 of themodule 40 (see FIGS. 7-9). Preferentially, at the front and at the back(or at on non-inclined sides) of the formation 31, a projection 36 isprovided, which preferably surrounds the intermediate cavity 32, whenthe latter is envisaged (visible in the figure is just the frontprojection of the formation 31; the rear projection may have a similarshape). Preferably, the projections 36 and/or the upright parts 33, 34define contrast and/or positioning surfaces or seats 31 a (FIG. 18) forthe optical module 40, in particular in an area from which theappendages 35 rise.

Preferentially, even though this is not strictly indispensable, the site30 comprises two recesses or seats 30 a defined in the bottom wall 21,each at an upright part 33, 34, alongside the corresponding inclinedsurface 33 a, 34 a. Very preferably, defined at at least one of theaforesaid recesses 30 a is a positioning and/or centring and/or contrastand/or engagement element 37 for the lower end of a correspondinglateral body 46, 47 of the module 40, in particular for thecorresponding lower projections 46 b, 47 b (see FIGS. 8 and 9).

During assembly, the circuit support 15 with the associated opticalmodule 40 is inserted in the body 10 a, with the support itself thatpenetrates between the seats 22, preferably until abutting against theinner side of the wall 21.

In the course of this insertion, the upper appendages 35 of the uprightparts 33, 34 (FIG. 18) penetrate into the through openings 51 a of thecentral body 45 of the module 40 (FIGS. 7-9), and the wall 52 a of thelower formation 52 of the aforesaid central body 45 (FIGS. 8-9)penetrates into the intermediate cavity 32 that separates the uprightparts 33 and 34 of the optical formation 31 from one another (FIG. 18).The walls 52 b of this formation 52 slide on the projections 36 of thefront and back of the formation 31 (FIG. 18), thus contributing tocentring.

Contact or abutment in the vertical direction between the module 40 andthe formation 31 occurs in the upper part, with the lower surface of thecentral body 45 of the module 40 that comes to bear upon upper surfacesof the upright parts 33, 34, i.e., surfaces from which the appendages 35project in height (these surfaces may be appreciated in FIG. 18, two ofwhich are designated by 31 a). Preferentially, provided in the lowerpart is at least one surface for abutment in a radial direction, alsowith the aim of positioning or countering rotation of the optical module40 with respect to the site 30: this contrast surface is preferablyobtained via the lower projections 46 b and 47 b (FIGS. 8 and 9) of thelateral bodies 46 and 47 of the module 40, which engage in the elementsor seats 37 defined at the recesses 30 a (FIG. 18), possibly with theprovision of mutual-engagement means between the elements 46 b, 47 b andthe elements 37. In this way, the module 40 is not able to turn and canremain in the desired position.

The flexibility of the conductors 48, 49 and of the terminals 50 of themodule 40 is particularly advantageous in this step, in so far as itenables compensation of possible dimensional tolerances involved inproduction of the parts and in assembly of the module itself on thecircuit support 15, which are relatively high in devices comprising anumber of moulded parts made of plastic material, thereby preventing anyfailure during assembly and/or enabling precise positioning of theoptical module 40.

A partially assembled condition is visible in FIG. 19, from which it maybe noted how, in the position described, the body 46, and hence theemitter 42, on the one hand, and the body 47, and hence thephotodetectors 44 a, 44 b, on the other, are set facing and generallyparallel to the inclined surfaces 33 a and 34 a of the two upright parts33 and 34, respectively. Next, and as may be seen in FIG. 20, fitted onthe formation 51 defined at the upper face of the central body 45 of theoptical module 40 is the aforementioned elastic blocking and/orpositioning element 60, hereinafter also defined for simplicity as“spring”, preferably made of metal material. The spring 60 has a centralpart 61 provided with a tabbed hole (i.e., an opening defined by elasticradial tabs) in order to enable fixing thereof with interference on theformation 51 itself. It is preferable for the tabs of the hole to besized also to enable fixing with interference fit also with the outersurface of the appendages 35 which projects in a position correspondingto the formation 51 (see FIG. 20).

Branching off from the central part 61 of the spring 60 are generallycurved opposite elastic arms 62, designed to exert a force on thelateral bodies 46 and 47 of the module 40. The ends 62 a of the arms 62are for this purpose preferably shaped for being received in the grooves46 a and 47 a (FIG. 7) of the lateral bodies 46 and 47 of the module 40,respectively. Preferably, the aforesaid ends 62 a are curved, also inorder to be able to slide in the grooves 46 a and 47 a during assembly.As may be appreciated, in this way, the optical module 40 is fixed inposition with respect to the formation 31 (and/or to the site 30, and/orto the inclined surfaces 33 a, 34 a, and/or to the wall 21, and/or tothe body 10 a), as may be seen in FIGS. 20 and 21.

The force exerted by the arms 62 of the spring 60 is able to bend theconductors 48, 49 of the module 49 (FIGS. 7-9), guaranteeing that thebodies 46 and 47 bear upon the body 10 a. For this purpose, both theconfiguration of the conductors 48, 49 and the configuration of thespring 60 are predefined to guarantee the aforesaid bending of theconductors and/or the aforesaid positioning. With reference to FIG. 21,the force exerted by the spring 60 guarantees, on the side of theemitter 42, contrast and positioning between the space filter 43 and theoptical surface represented by the inclined surface 33 a. On the side ofthe receiver 44 a-44 b, the force of the spring 60 guarantees contrastbetween the lower projection 47 b of the body 47 of the module 40 andthe corresponding contrast surface 37 defined in the wall 21.

Provision of the two contrast elements mentioned, together with the useof the spring 60, guarantee recovery of possible tolerances derivingfrom assembly and production of the components in such a way as toobtain a precise position of the optical components 42 and 44 a, 44 b.The position of these components—which is linked to the critical angleenvisaged by the application, as described hereinafter—affectscalibration of the sensor for detecting the quality of the liquidsolution and must thus be definite and precise so as not to generateerrors of measurement. The spring 60 also guarantees recovery of anyplay and deformation that may be generated during the service life ofthe device 10, owing to thermal cycles and/or ageing of the materials.Obviously, also the flexibility of the conductors 48, 49 and of theterminals 50 contributes to recovery of tolerances and play.

In preferred embodiments, the intermediate cavity 32 of the formation 31is provided in order to shield the receiver 44, i.e., the photodetectors44 a, 44 b, from direct irradiation by the emitter 42 (i.e., withoutthere being any incidence on the solid/liquid interface surface, asclarified hereinafter). This cavity 32, when envisaged, may hence nothave just the centring function for the optical module 40 but, alsothanks to the interposition of the wall 52 a of the lower formation 52of the module 40 (see once again FIGS. 8-9), could cause the aforesaidwall to operate as shield against parasitic emissions, as may clearly beappreciated for example from FIG. 21. Possibly the walls of theintermediate cavity 32 or some walls of the formation 31 may be at leastin part coated with a material or paint impermeable to opticalradiation, or else be shaped so as to deflect the rays of the emitter 42in such a way that these do not reach the receiver 44 directly.

Preferably, shielding of the direct emissions is further improved by theuse of the space filter 43. The use of at least one of such shieldingelements represented by the cavity 32 and/or by the filter 43 couldenable the use of lower-quality and less costly emitters 42, in so faras they are not designed or selected for emissions within a narrowangle. Such an emitter 42 could in fact be of the type that emits in adistributed way in all directions (0-180°) and, in addition to the spacefilter 43, the intermediate shield represented by the wall 52 a preventsthe light rays not involved in the measurement (i.e., the rays differentfrom the ones reflected and refracted by the solid/liquid interfacesurface, as explained hereinafter) from possibly altering themeasurement made via the photodetectors 44 a, 44 b.

Operation of the quality optical sensor integrated in the device 10according to the invention is based upon the optical laws linked torefraction/reflection of optical radiation, and in particular to thecritical angle of total reflection. More in particular, the operatingprinciple is based upon the dependence of the refractive index of theliquid substance upon its composition or concentration: the measurementis hence based upon the jump in the refractive index between the liquidto be analysed and the solid material in which the optical formation 31,as well as the corresponding part of the bottom wall 21 of the body 10 a(i.e., its part that is occupied by the optical positioning site 30 ofthe optical module), is defined, exploiting the principle of total innerreflection within the interface between the two media.

If

-   -   n₁ is the refractive index of the aforesaid solid material        (e.g., for a COC at 25° C., n₁=1.5413 at the wavelength of 650        nm),    -   n₂ is the refractive index of the liquid solution, which        presents a range of variation comprised between two limits        according to its concentration (e.g., for urea we may consider a        range of variation between 1.3626 and 1.3949 corresponding to a        concentration between 20% and 40%),    -   θ₁ is the angle of incidence (propagation of light in the        solid), and    -   θ₂ is the angle of deflection of the refracted beam (propagation        of light in the liquid),    -   the angle of propagation in the liquid medium will depend upon        the angle of incidence, at the interface, of the beam that        propagates in the solid medium, as expressed by Snell's law:

n ₁ sin θ₁ =n ₂ sin θ₂  1)

The coefficient of reflection at the interface between the two materialsas a function of the angle of incidence for the polarization p(parallel) and the polarization s (normal) of the light is expressedinstead by Fresnel's law:

$\begin{matrix}{R_{s1} = \left( \frac{\sin \left( {\theta_{2} - {\theta_{1}.}} \right)}{\sin \left( {\theta_{2} + \theta_{1}} \right)} \right)^{2}} & \left. 2 \right) \\{R_{p\; 1} = \left( \frac{\tan \left( {\theta_{2} - {\theta_{1}.}} \right)}{\tan \left( {\theta_{2} + \theta_{1}} \right)} \right)^{2}} & \left. 3 \right)\end{matrix}$

The intensity of the reflected ray is constituted by the composition ofthe two states R_(s) and R_(p). By computing Eqs. 2 and 3 for each angleof incidence and for each value of the refractive index of the liquidsolution within the range of interest, it is possible to know the(percentage) value of the reflectivity as a function of the angle ofincidence of the light beam. The angle of incidence at which Eqs. 2 and3 generate a value of reflectivity of 100% is referred to as “criticalangle of total inner reflection”.

Since there exists a limit condition for the angle of incidence at thesolid/liquid interface where the angle of refraction is tangential tothe interface itself, n₁ must be greater than n₂, as in the situation ofinterest for the application considered herein, where propagation fromsolid to liquid is considered. For an incidence with an inclinationgreater than the critical angle, the beam is totally reflected at theinterface.

It may be found that the critical angle of refraction at the interfaceis expressed by the relation:

$\begin{matrix}{\theta_{c} = {\arcsin \left( \frac{n_{2}}{n_{1}} \right)}} & \left. 4 \right)\end{matrix}$

which represents the condition where the value of reflectivity—as theangle of incidence θ₁, calculated by applying Eqs. 2 and 3,varies—reaches 100%.

Computing Eq. 4 for all the values of n₂ of interest, where n₂ is therefractive index of the liquid solution, which depends upon itsconcentration, it is possible to link the value of the concentration tobe measured to the position of the reflected light beam at thesolid/liquid interface.

In particular, the following relations apply:

$\begin{matrix}{\left. {{Conc}\mspace{14mu} 1}\Rightarrow n_{2} \right. = {\left. N_{21}\Rightarrow\theta_{c1} \right. = {\arcsin \left( \frac{N_{21}}{n_{1}} \right)}}} & \left. 5 \right) \\{\left. {{Conc}\mspace{14mu} 2}\Rightarrow n_{2} \right. = {\left. N_{22}\Rightarrow\theta_{c2} \right. = {\arcsin \left( \frac{N_{22}}{n_{1}} \right)}}} & \;\end{matrix}$

If Conc 1>Conc 2 then the following relation applies:

N ₂₁ >N ₂₂⇒θ_(c1)>θ_(c2)

On the basis of what has been recalled here, it is hence possible toexploit the existence of a critical angle of total reflection thatvaries as the concentration varies for measuring the concentrationitself, by applying the relations of Eq. 5.

For this purpose it is possible to use a light source—i.e., an emitter42—with divergent output so as to illuminate the interface surface atall the angles of interest around the critical angle, and hence with anincidence that is greater and less than the critical angle. In this way,there will exist two areas: an area impinged upon by the totallyreflected rays (which derive from the rays having an angle of incidencegreater than the critical angle) and an area impinged upon with a lowerintensity, which is illuminated by the partially reflected rays (whichderive from the rays having an angle of incidence of less than thecritical angle). There may thus be obtained, at output, a region ofillumination in which the separation between the area highly illuminatedby total inner reflection and the area less illuminated (partialreflection) is variable as a function of the concentration of theliquid.

Hence, using the two photodetectors 44 a and 44 b, positioned in the twoareas, through the variation of their output signal it is possible toevaluate the variation of the critical angle and consequently thevariation of composition or concentration—and, in the ultimateanalysis—of the quality of the liquid substance or solution.

The inclination of the optical surfaces 33 a and 34 a is preferablycalculated in such a way that the optical signal traverses them in adirection as far as possible orthogonal to the surfaces of entry andexit of the light, so as to minimise the reflection at the air/solid andsolid/air interfaces, respectively.

The emitter 42 is preferably a light source with a narrow emission beamin order to concentrate the measurement in the area of interest (aroundthe critical angle), according to the direction identified as a functionof the critical angle (however, as mentioned previously, thepreferential use of filters and/or shieldings enables the use also oflight sources with wider emission beam). In this way, also anyinterference due to direct irradiation of the photodetectors 44 a and 44b is minimised. In various embodiments, it is preferable to usenon-diffused lambertian sources, i.e., sources with uniform lightemission in space without holes or alterations in the near field. Toexploit the practically constant area of maximum intensity of the sourceand restrict the emission in the area around the critical angle, alsothe space filter 43 is preferably introduced.

The path of the light rays can be represented schematically asexemplified in FIGS. 22 and 23.

In the above figures, there appear two rays R1 and R2 contained withinthe range of emission of the source, which are incident on the surfaceof separation between the solid and the fluid (i.e., the outer side—heredesignated by 21 ₁—of the bottom wall of the cavity H) with twodifferent angles; the angles of the rays R1 and R2 are, respectively,smaller and greater than the critical angle. Given that the ray R1 hasan angle of incidence lower than the critical angle, it will berefracted in the ray R1 ₁ and reflected in the ray R1 ₂. By the law ofconservation, the intensity of the ray R1 will be distributed betweenthe ray R1 ₁ and the ray R1 ₂. The ray R1 ₂ will be detected by a firstphotodetector 44 a, also defined hereinafter for simplicity as “upperphotodetector”. The ray R2, instead, is incident with an angle greaterthan the critical angle and will hence be totally reflected in the rayR2 ₁. Unless in case of dissipation, the ray R2 ₁ will have the sameintensity as the ray R2. The totally reflected ray will be detected bythe second receiver 44 b, also defined hereinafter for simplicity as“lower photodetector”.

The rays used for the schematic representation appearing in FIGS. 22 and23 form part of a region of illumination that changes its configurationas a function of the variation of the critical angle (namely, of therefractive index of the liquid solution), i.e., of the concentration ofthe liquid solution. Exemplified for greater clarity in FIGS. 24, 25,and 26 are three working conditions, linked to three differentconcentrations of the fluid.

In the presence of a liquid substance or solution with a firstcomposition or concentration Conc 1 the scheme represented in FIG. 24 isobtained: assuming that the rays of the beam R impinge upon the surfaceof interface with an angle equal to the critical angle, the rays R₁, R₂,and R₃ are obtained as total reflection of the incident rays, whereasthe rays R₄ and R₅ are obtained as partial reflection of the incidentrays. The lower receiver 44 b will hence be completely illuminated bythe totally reflected rays, whereas the upper receiver 44 a will receivea lower intensity or radiation produced by the partially reflected rays.

FIG. 25 represents schematically a condition in which a secondconcentration of the liquid substance or solution is equal to Conc 2,where Conc 2 is smaller than Conc 1. The rays of the illuminating beam Rproduced by the emitter 42 always present the same angle of incidence,while the critical angle decreases. It follows that, in addition to therays R₁, R₂, and R₃, there will be obtained also the ray R₄ by totalreflection, whereas the ray R₅ will continue to be obtained by partialreflection. In this condition, the intensity of radiation on the upperreceiver 44 a will be increased, whereas the one on the lower receiver44 b will remain unchanged.

Finally, FIG. 26 represents schematically a condition where a thirdconcentration of the liquid substance or solution has a value Conc 3,which is greater than Conc 1. Also in this case the rays of theilluminating beam R produced by the emitter always present the sameangle of incidence, while the critical angle increases. It thus followsthat the rays R₁ and R₂ will always be obtained by total reflection,whereas the ray R₃ will be obtained by partial reflection, like the raysR₄ and R₅. In this condition, the intensity of radiation on the upperreceiver 44 a will be reduced, whereas the one on the lower receiver 44b will remain unchanged. By further increasing the concentration of thefluid, the percentage of totally reflected rays will decrease, and alsothe signal on the lower receiver 44 b will vary. In this condition, theintensity of radiation on the upper receiver 44 a will be reduced,whereas the one on the lower receiver 44 b will remain unchanged. Byfurther increasing the concentration of the fluid, the percentage oftotally reflected rays will decrease, and also the signal on the lowerreceiver 44 b will vary.

Consequently, as may be appreciated, the photodetectors 44 a and 44 bare positioned so as to receive each a part of the reflected light beam,one of the photodetectors receiving radiation at high intensity, whichis the light incident with an angle greater than the critical angle, andthe other receiving radiation at low intensity, which is the light onthe “tail” of the profile of radiation.

On the basis of what has been set forth above, if A and B are thevoltage signals at output from the photodetectors 44 a and 44 b, it iseasy to understand that they contain a term that depends upon theoptical power P emitted by the source 42. A and B are in fact voltagesignals generated by the value of photo-current, i.e., of electriccurrent of the photodetectors upon which the light impinges, multipliedby the transimpedance gain. The photo-current is proportional to theoptical power P emitted by the source 42, multiplied by the response(responsivity) of the photodetector 44 a or 44 b, namely:

A=ka*P·response*transimpedance

B=kb*P·response*transimpedance

where ka and kb are coefficients that take into account the amount oflight incident upon the photodetector 44 a or 44 b, which will be afunction of the refractive index and hence will be variable as afunction of the critical angle.

To eliminate the dependence upon P and thus obtain a signal that dependsonly upon the position of the centroid of the region of illumination,irrespective of the peak intensity value, it is sufficient to introducea normalized signal. This signal may be correlated, for example via anappropriate calibration that can be performed on the basis of predefineddata, to the variation of concentration of the liquid substance orsolution undergoing detection, which is hence independent of theilluminating power P. It is convenient to eliminate the dependence uponthe intensity of the optical power so that the measurement will not beaffected by any disturbance linked to variations (e.g., thermalvariations or variations due to degradation over time) in the emissionof the source 42.

The two signals A and B produced by the photodetectors 44 a and 44 b arepreferentially treated by an analog conditioning network so as adaptthem to the electronic controller MP, which is able to generate a signalS that is directly correlated, via appropriate calibration, to theconcentration of the liquid solution.

FIG. 27 provides an example of operating block diagram of the qualityoptical sensor. In this figure, designated by Vcc is the low-voltagesupply of the emitter 42, whilst the block OG represents the opticalgeometry provided by the positioning site 30 (formation 31 andcorresponding wall portion 21). As may be noted, the voltage signals Aand B at output from the photodetectors 44 a, 44 b are treated by aconditioning circuit CC, and the conditioned signals A1 and BI reachcorresponding inputs of the controller MP, which generates the signal Srepresenting the value of concentration of the solution. The componentsCC and MP are preferably located on the circuit support 15, with thecontroller MP that manages detection of quality of the liquid substanceor solution. The components CC and MP may also be integrated in a singlemicrocontroller component.

In various embodiments, the connection between an optical module of thedevice 10 according to the invention and the corresponding interfaceand/or control circuit, such as the one provided on the circuit support15 and/or the circuit arrangement 17, can be obtained via wiring,namely, electric wires, instead of terminals, preferably externallyinsulated wires. An embodiment of this type is, for example, illustratedin FIGS. 28-33, where the same reference numbers as those of theprevious figures are used to designate elements that are technicallyequivalent to the ones already described above.

The use of electric wires enables the circuit board 15 to be keptseparate from the optical module in order to be able to mount themseparately, for making the wired connection between them after assemblyof the two parts. Preferably, and as may be evinced in particular inFIGS. 31-33, the connection holes 53 are provided in lateral positionsof the circuit support 15, to which the aforesaid electric wires—some ofwhich are designated by 50 ₁ in FIG. 33—may, for example, be soldered.The holes 53 may also be replaced by metallized pads or small pins. Thedimensions of the circuit support 15, in particular its height, may besmaller than in the case illustrated previously.

In view of the use of electric connection wires, the body 45 of theoptical module 40 is slightly modified with respect to what has beenillustrated previously. In particular, the terminals previouslydesignated by 50 are shorter and are prevalently embedded in the plasticmaterial that constitutes the body 45 (see, for simple reference, FIGS.37 and 38, as regards a further embodiment). Preferentially, theseterminals have through holes (or pads) in respective end regions, andthe central body 45 of the module 40 is moulded so as to leave theaforesaid holes (or pads) accessible, as may be seen, for example, inFIGS. 31 and 32, where designated by 50 ₂ are some of the passages ofthe body 45 that enable access to the aforesaid holes of the embeddedterminals in order to enable connection of the electric wires (for anembodiment of this sort, see, for example, also FIGS. 38 and 50).

In embodiments of this sort it is preferable first for the circuit board15 to be inserted in the seats 22, and then the optical module 40 ispositioned and fixed on the formation 31 in a way substantially similarto what has already been described previously, via the spring 60. Thenext step is to connect the electric wires 50 ₁ between the circuitsupport 15 and the module 40. The wires 50 ₁ may, on the other hand,also be connected on the optical module 40 prior to mounting thereof onthe formation 31. The operating principle of the device, as regardsdetection of the quality of the liquid solution, is similar to what hasbeen described previously.

The advantage of solutions that entail the use of electric connectionwires affords greater flexibility in the coupling between the opticalmodule 40 for measurement of the concentration and the circuit support15 (on the other hand, instead of the aforesaid electric wires therecould be provided other electrical connections or terminals, for examplein the form of terminals obtained from a blanked metal strap or stampedor machined metal; electrical terminals of this sort could possiblyenvisage an overmoulded body, distinct from the bodies 45-47 of theoptical module 40).

In various embodiments, provided within the cavity of the body of thesensor device is an optical shield, preferably of a dark colour orimpermeable to optical radiation or light at a predefined frequency,which performs the function of shield from ambient light.

FIGS. 34-48 illustrate a variant embodiment in this sense. Also in thesefigures the same reference numbers as those of the previous figures areused to designate elements that are technically equivalent to the onesalready described above, in particular as regards the relative positionbetween the formation 31 and the opening 22, as well as the type ofelectrical connection of the optical module 40 to the circuit support15, i.e., its arrangement 17. The embodiments described with referenceto FIGS. 34-48 are basically distinguished by the presence, within thecavity H, of a shield or body aimed at limiting diffusion of ambientlight, as well as by a different mode of fixing in position of theoptical module 40, as compared to the previous embodiments.

With initial reference to FIG. 34, the body 10 a and the circuit support15 may be of a construction substantially similar to the one describedwith reference to FIGS. 2-27, as likewise the basic structure of theformation 31, the upper appendages 35 of which have external recesses.

The optical module 40 is substantially similar to that of FIGS. 28-33,possibly with some modifications that depend upon its mode of fixing inposition: for example, in various embodiments, the module 40 may besecured in position via a different elastic element or spring 60 ₁ andan arrest or retention ring 80, in particular an elastic retaining ringor circlip (Seeger).

The aforesaid optical shield, designated as a whole by 70 in FIG. 34, isrepresented in detail in FIGS. 35-36. The shield 70 has a body 71preferably made of a material that is not permeable to optical radiationof predefined wavelengths, such as a dark material or in any case amaterial that is able to limit or prevent passage of ambient light. Thebody 71 has a bottom wall 72, designed to rest on the wall 21 of thebody 10 a, and a peripheral wall 73, preferably but not necessarily witha profile corresponding to at least one part of the peripheral wall 20of the body 10 a (FIG. 34). In the example, this profile issemicircular, with a diameter slightly smaller than that of the wall 20,or possibly such as to enable insertion with slight interference.

Defined in the bottom wall 72 is a lateral passage or recess 72 a,shaped in such a way that the wall 72 does not interfere with or coverthe positioning site 30 of the bottom wall 21 of the body 10 a.Projecting in cantilever fashion within the recess 72 a is asubstantially frame-like structure 74, designed to be fitted on theoptical formation 31. For this purpose, the structure defines two upperopenings 74 a, in which there may partially penetrate the upright parts33 and 34 of the optical formation 31, these openings being separatedfrom one another by an intermediate wall 74 b, which can be received inthe intermediate cavity 32 of the formation 31 (see FIG. 39, forreference to the aforesaid upright parts and intermediate cavity).

The frame-like structure 74 of the shield 70 has further lateralpassages 74 c, which are designed to face at least part of the inclinedoptical surfaces 33 a and 34 a of the formation 31.

The optical module 40 is, instead, illustrated in FIGS. 37 and 38. Asmay be evinced, its basic structure is similar to that of the moduleappearing in FIGS. 28-33. In various embodiments, the central body 45 ofthe module 40 defines an opening 45 a for positioning of an arrestelement of a spring 60 ₁, in particular, defined between the upperformation 51 and the area in which the passages 50 ₂ for connection ofthe electric wires (designated hereinafter by 50 ₁) for interfacing tothe circuit 15 are defined. Once again preferentially, on at least oneside of the opening 45 a the upper face of the central body 45 has aprojection 45 b that performs functions of arrest for the retaining ring80 (FIG. 34).

For the purposes of assembly, the shield 70 is inserted in the cavity Hof the body 10 a, with its bottom wall 72 facing the bottom wall 21 (asin FIG. 39) in such a way that the upper appendages 35 of the opticalformation 31 penetrate into the passages 74 a of the frame-likestructure 74 of the shield itself, and the intermediate wall 74 b of theshield penetrates into the intermediate cavity 32 of the formation 31itself. Following upon positioning of the shield 70, as may be seen inFIG. 40, the recesses or seats 30 a and possible further parts of theoptical site 30 remain exposed (via the recess 72 a of the shield);moreover the lateral openings 74 c are set facing the inclined opticalsurfaces 33 a and 34 a of the optical formation 31.

The circuit 15 is then inserted in the seats 22 and the module 40 isfitted on the formation 31, as has already been described previously andas may be seen in FIG. 41. Fixing may be carried out using a spring ofthe same type as the ones mentioned previously and designated by 60.Alternatively, positioned on the upper formation 51 of the module 40 isthe spring 60 ₁, having a shape slightly different from that of the onespreviously designated by 60, but having a structure and functions thatare substantially similar, and the aforesaid spring is then blocked inposition via a ring 80, as may be seen in FIG. 42. Next, the module 40is connected to the circuit support 15 via the electric wires 50 ₁, ashas already been described previously and as may be seen in FIG. 43.

As has been said, the plastic component 70 performs the function ofshield against ambient light, which may derive from any light emissionexternal to the device 10 and/or to the optical module 40. Given thatthe operating principle of the quality optical sensor is based upondetection of optical radiation, the possibility of having “parasitic”ambient light that impinges upon the liquid solution and/or upon thephotodetectors 44 a, 44 b may disturb the measurement. This conditionmay arise, for example, with application of the device according to theinvention on transparent or non-opaque tanks, or if the entire body 10 aof the device 10 is made of a material permeable to light emission:ambient light can hence illuminate the fluid and/or the photodetectors44 a, 44 b through the walls of the tank, and/or parts of the body 10 a,and thus disturb the measurement. The plastic shield 70, mounted withinthe body 10 a, enables, for example, shielding from ambient light,thereby eliminating any risk of disturbance due to ambient light.

FIG. 44 represents a possible embodiment of the spring 60 ₁. Also inthis case, the structure of the spring includes a central part 61,branching off from which are two opposite arms 62, the ends of which areshaped for engagement in the corresponding seats 46 a, 47 a provided onthe outer face of the lateral bodies 46, 47 of the module 40 (see FIGS.37-38). Preferably, these ends 62 a are curved, also so that they canslide in the grooves 46 a and 47 a during assembly.

In this case, preferentially the central part 61 has a hole or opening,the profile of which substantially corresponds to the outer profile inplan view defined by the upper formation 51 of the module 40 and by theupper appendages 35 of the optical formation 31 (it should be noted thatin this embodiment the passages 51 a of the body 45 of the module40—FIGS. 37-38—and the aforesaid appendages 35 are configured in such away that the appendages project laterally, to an appreciable extent,beyond the outer profile of the formation 51: see for reference FIG.41). Furthermore, projecting on one side of the central part 61 of thespring 60 ₁, here the front side, is an arrest element 61 b, here in theform of tab bent downwards, like a tooth.

Represented in FIG. 45 is a possible embodiment of the retaining ring80. In preferred embodiments, the ring 80 is substantially a circlip(Seeger), i.e., a ring—preferably made of metal, very preferably ofelastic steel—having a generally flat configuration, the circumferenceof which is not complete and, in its two end regions, holes are definedfor insertion of a suitable tool for application and removal thereof,such as circlip pliers (Seeger plier). In the case illustrated,according to a characteristic in itself inventive, at least the internalprofile of the ring 80 substantially reproduces part of the profile ofthe opening 61 a of the spring 60 ₁ and/or is complementary to part ofthe aforesaid outer profile in plan view of the upper formation 51 andof the upper appendages 35, hence presenting a substantially circularprofile with two opposite projections or recesses 80 a. At one end,beyond the corresponding hole, the ring 80 defines a detent projectionor seat 80 b. Preferably, moreover, the other end of the ring, which isprovided with a hole, defines an outer contrast surface 80 c. At leastone of the projection or seat 80 b and the contrast surface 80 c definesanti-rotation means for the ring 80.

It should again be noted how, in particular from FIG. 40, in variousembodiments of the invention, the upper appendages 35 of the formation31 present, in their upper end region and at their outer side, a lateralrecess, designated by 35 a (see, merely for reference, also FIG. 79).

As has already been pointed out, the spring 60 ₁ performs the samefunctions as the ones already described previously, but it is notmounted via interference fit on the formation 51 of the optical module40, given that it is blocked by the ring 80. FIGS. 46-48 highlight apossible sequence of assembly of the spring 60 ₁ and of thecorresponding retaining ring 80.

After the module 40 has been fitted on the optical formation 31,preferably with the structure 74 of the shield 70 set in between, thespring 60 ₁ is fitted on the module, so that the formation 51 and theprojecting part of the appendages 35 are inserted in its central opening61 a (see FIG. 44), as in FIG. 46. With this insertion, moreover, theelement 61 b of the spring engages in the opening 45 a of the centralbody 45 of the optical module 40, thereby having the function ofpreventing rotation of the spring 60 ₁.

Then, fitted on the formation 51 and on the appendages 35 is the ring80, in an angular position thereof that enables its insertion, as inFIG. 47. In practice, in this angular position of the ring 80, its twoprojections or recesses 80 a (FIG. 45) are in a position correspondingto the appendages 35; i.e., the internal profile of the ring 80corresponds to part of the outer profile defined by the formation 51 andby the appendages 35. Next, for example by exploiting the two holes ofthe ring 80 and using a normal pair of circlip pliers, the ring itselfis made to turn in such a way that the latter engages the lateralrecesses 35 a of the appendages 35 (see FIG. 40) and until its detentprojection 80 b and the contrast surface 80 c encounter the projections45 b defined on the upper face of the body 45 of the module 40. Thisfinal blocking situation is highlighted in FIG. 48.

The clamping system described with reference to FIGS. 44-48 enablesreduction of the overall dimensions of the spring and avoids fixingthereof with mechanical interference fit, which could cause possibleproblems of failure or damage to the plastic material of which theformations 31 and/or 51 are made. This type of fixing of the spring isregardless of the presence of an optical shield of the type designatedby 70 and can be employed also in the other embodiments described hereinthat envisage the use of an optical module substantially of the typedesignated by 40 and/or other devices. As has been mentioned, on theother hand, there is nothing, in principle, to rule out the use also inthe device of FIGS. 34-48 of an elastic fixing element of the typedescribed with reference to the previous FIGS. 2-33. Furthermore, ashield of the type described, also having a shape different from the oneexemplified, but with the same purposes may be used in all theembodiments described herein.

In various embodiments of the invention, a fixing element of an opticalmodule is configured for being secured in position, with respect to anoptical formation, by means of an angular movement thereof. Possibleembodiments of this type are described with reference to FIGS. 49-60.Also in these figures the same reference numbers as those of theprevious figures are used to designate elements that are technicallyequivalent to the ones already described.

As may be seen in FIGS. 49-50, in various embodiments lateral bodies 46₁ and 47 ₁ of the module 40 are provided, which have, at at least onelateral region, a lead-in surface 46 c, 47 c, for example an inclinedsurface or a curved surface, which extends towards the upper face of thebody itself. Preferentially, the lead-in surface 46 c is defined in thebody 46 ₁ in a position opposite to the lead-in surface 47 c defined inthe body 47 ₁. For the rest, the optical module 40 is obtained in a waysubstantially similar to what has been described with reference to theprevious embodiments, with the central body 45 that defines at the upperthe formation 51 and at the bottom the formation 52, with the throughopenings 51 a. Also in this case, the terminals 50 are preferablyembedded, to a major extent, in the plastic material of the body 45 andhave in respective end areas solder pads or holes aligned to passages 50₂ of the body 45.

In preferred embodiments, defined at at least one edge of the body45—here the front edge—is a positioning recess 45 a ₁, the functions ofwhich will appear clearly hereinafter. Also the site 30, or the opticalformation 31 (FIGS. 58-59), is similar to the one described withreference to FIGS. 32-44, in particular as regards the presence oflateral recesses 35 a in the upper end regions of the appendages 35.

Also in embodiments of this type, the module 40 is fitted on theformation 31 with modalities similar to the ones described previously,but fixing is obtained via an elastic blocking and/or positioningelement having a different configuration, a possible embodiment of whichis visible in FIG. 51, where the aforesaid spring element is designatedas a whole by 60 ₂.

Also in this case, the elastic element 60 ₂ has a central part 61provided with a through hole 61 a and two elastically flexible oppositearms 62. Preferentially, the distal ends 62 a of these arms 62 are bentor in any case shaped in order to facilitate their sliding on the bodies46 ₁ and 47 ₁, in particular in an angular or rotary direction, asdescribed in what follows. The part 61 is shaped so as to define twoflexible tabs 61 c within the hole 61 a, in opposite positions,preferably in positions generally corresponding to those of the arms 62.The tabs 61 c, here having a substantially arched configuration, eachfollow part of the profile of the hole 61 a, this profile moreoverpresenting a pair of widened portions in diametrally opposite positions,each substantially at the free end of each tab 61 c. Preferentially,moreover, branching off from the central part 61 is an appendage 61 e,set generally transverse or orthogonal to the arms 62. The elasticelement 60 ₂, like the ones described previously, is preferentially madeof metal, starting from a blanked and deformed strap.

As may be seen in FIGS. 52 and 53, the element or ring 60 ₂ is fitted onthe formation 51 of the module 40 and on the projecting part of theappendages 35 that projects at the sides of the formation. This isallowed by the presence of widened portions 61 d, which in this step arein positions corresponding to the aforesaid appendages. Next, the springis turned (in a counterclockwise direction, as viewed in FIGS. 53-57),in such a way that first the edge of the hole of the spring—FIG. 54—andthen that of the tabs 61 c-FIG. 55—penetrates into the recesses 35 a ofthe appendages 35 (see also FIGS. 58-59). At a certain point of theangular movement, the free ends of the arms 60 of the spring come tointerfere with the lead-in surfaces 46 c and 47 c, as may be seen inFIG. 55. As has been said, the ends 62 a of the arms 62 are preferablycurved or shaped to facilitate sliding and/or prevent any sticking: inthe example, these ends are bent substantially to form a C.

The prosecution of the angular movement of the spring 60 ₂ is thenallowed by the presence of the inclined or curved lead-in surfaces 46 c,47 c, which in this step function as chute, with the ends 62 a of thespring that can slide as far as on the upper face of the bodies 46 ₁ and47 ₁, as may be seen in FIG. 56. In this way, an elastic bending of thearms 60 is brought about, i.e., a preloading thereof, which urges thebodies 46 ₁ and 47 ₁, and hence the module 40 as a whole, onto thecorresponding formation 31: the optical filter 43—and hence the body 46₁—is elastically pressed on the inclined surface 33 a, whereas the lowerappendage 47 b of the body 47 ₁ is elastically pressed on thecorresponding contrast 37 (see FIG. 58).

When the ends 62 a of the two arms 62 of the spring 60 ₂ are in thesubstantially central positions of the upper faces of the bodies 46 ₁and 47 ₁, i.e., the spring 60 ₂ is in the right position, in therecesses 35 a of the appendages 35, terminal end regions of the tabs 61c are in any case engaged, and the appendage 61 e that branches off atthe front from the spring 60 ₂ is aligned with the recess 45 a ₁, as maybe seen in FIG. 56. The spring may then be secured in position bycausing a plastic deformation of the appendage 61 e, in the sense ofengaging it in the recess 45 a ₁, as may be seen in FIG. 57. Next, thecircuit support 15 can be inserted in the corresponding seats 22 (FIG.52), as may be seen in FIGS. 58-59. Then, the optical module 40 can beelectrically connected to the circuit support 15 via the electric wires50 ₁, as in FIG. 60, with the modalities already described.

Of course, the fixing system described with reference to FIGS. 49-59 canbe used also in other embodiments described herein of the deviceaccording to the invention.

In embodiments so far described, the emitter 42 and the receiver 44 a-45a of optical radiation of the optical module 40 are set in a positioncorresponding to the lower face of the corresponding supporting bodies46 or 46 ₁ and 47 or 47 ₁. However, in various embodiments, an oppositeconfiguration is possible, i.e., with the emitter and receiver at theouter face of the aforesaid supporting bodies. Possible embodiments ofthis type are described with reference to FIGS. 61-71, where the samereference numbers as those of the previous figures are used to designateelements that are technically equivalent to the ones already describedabove.

In various embodiments of this type, the emitter and receiver electroniccomponents used have a respective package, of the type commonly referredto as “reverse gullwing”. This possibility can advantageously beexploited to integrate a space filter—for example, of the typespreviously designated by 43—directly in the structure of the opticalmodule 40, assembling the emitter 42 and/or the receiver 44 a-44 b atthe outer face of the corresponding supporting bodies 46, 47. Theoperating principle of the module 40 does not change with respect to theversions described above, and also the basic elements of the opticalsensor preferably maintain the same characteristics already described,even with slightly different shapes. The spring used may be of the typepreviously designated by 60.

As may be seen in particular in FIGS. 62-63, the structure of the module40 is substantially similar to the ones described previously, i.e., withthe central body 45 and the lateral bodies—here designated by 46 ₂ and47 ₂—overmoulded on conductors 48, 49 and terminals 50. In the caseexemplified, the lower formation of the central body 45, here designatedby 52 ₁, is slightly modified with respect to the previous versions, butis in any case distinguished by the presence of the transverse wall 52a, which is designed for coupling with the corresponding intermediatecavity of the optical formation 31. To enable centring and resting onthe formation 31, the walls 52 b of the embodiments illustratedpreviously are replaced by projections 52 b ₁ and by homologous axialribbings provided on a wall 52 b ₂ that extends orthogonally downwardsfrom the lower face of the body 45. The wall 52 b ₂, which may have aheight such that its lower edge rests on the wall 21 of the cavity H ofthe body 10 a in order to constitute a support for the module 40,advantageously also performs functions of rear shield from ambientlight, since the bodies 45-47 are preferably made of dark material or inany case of a material not permeable to visible light and/or to opticalradiation at predefined wavelengths.

The lateral bodies 46 ₂ and 47 ₂ are provided with through openings 46 dand 47 d in order to enable passage of optical radiation, as may benoted in particular in FIG. 63. According to an aspect in itselfautonomously inventive, the body 46 ₂ or at least the opening 46 d, alsoperforms the functions of space filter described previously; i.e., thebody 46 ₂ of the module 40 defines at least one through opening or hole,preferably circular or shaped like a slit, which filters and selects orconcentrates the light beam emitted by the emitter 42.

Assembly of the electronic components 42 and 44 a-44 b on the uppersurface of the bodies 46 ₂ and 47 ₂ entails the need to introduce aprotective surface in the area where the spring 60 is to exert itspressure. To prevent the spring 60 from exerting force directly on theaforesaid electronic components, in various embodiments a protectiveelement is used, designated as a whole by 90 in FIG. 61, which canadvantageously also perform functions of shield against ambient light.The spring will hence exert the force on the protective element 61 andindirectly also on the module 40. It should be noted that, since thespace filter 43 is no longer present, it is also preferable to ensurethat the lateral body 46 ₂ and the formation 31 bear upon one another inorder to guarantee always proper positioning of the components: for thispurpose, the lower appendage 46 b of the body 46 ₂ (see FIG. 63) and thecorresponding positioning element 37 are configured for bearing upon oneanother and/or defining the mutual positioning (see, for example, FIG.70).

A possible embodiment of the protective element or shield 90 is visiblein FIG. 64. With reference to the example illustrated, the shield has aplastic body 91, preferably dark or not permeable to light, having agenerally open annular shape—here approximately elliptical—defined inwhich are a bottom wall 92 and a peripheral wall 93. Rising from thebottom wall 92 is a front wall 94, which, in the assembled condition ofthe device, is located in front of the positioning area of the emitter42 and the receiver 44 a-44 b, in such a way as to produce a frontshield against ambient light. The shield 90 is shaped so as to defineupper appendages 95, generally inclined in opposite positions, whichdefine on their outer surface seats 95 a for the ends of the oppositearms of the spring 60. The appendages 95 are shaped so as to define asort of seat for housing and protecting the emitter 42 and thephotodetectors 44 a, 44 b, as will emerge hereinafter. The bottom wall92 is shaped so as to define an axial passage, for mounting in positionof the shield 90 after the module 40 has been mounted on thecorresponding formation 31. For this purpose, the peripheral wall 93also has an interruption 93 a.

In case of use of the shield 90, it is preferable for there to beprovided on the bottom wall 21 of the cavity H at least one positioningor contrast element for the shield itself, given that the spring 60exerts its own pressure thereon. In the case represented (see inparticular FIGS. 65 and 66), at least one positioning element 21 a,constituted by a wall that rises from the bottom 21 of the cavity H, isprovided for this purpose, the aforesaid wall 21 a here having a curvedshape, corresponding to part of the outer profile of the peripheral wall93 of the shield 90. The opposite part of the profile of the peripheralwall 93, which here includes two stretches separated by the interruption93 a, is compliant with the profile of the peripheral wall 20 of thecavity H: in this way, the shield 90 can be positioned between theelement 21 a and the peripheral wall 20. In the example illustrated,moreover, in the bottom wall 21 of the cavity H there are also definedfurther contrast elements 21 b for the shield 90, at the opposite endsof the site 30.

For the purposes of assembly, the module 40 is fitted on the formation31 with modalities similar to the ones that have already been describedpreviously, as represented schematically in FIGS. 65-66, after whichpositioned within the cavity H of the body 10 a is the shield 90, asrepresented schematically in FIGS. 66 and 67. The presence of theinterruption 93 a in the peripheral profile of the shield 90 is aimed atenabling or facilitating assembly of the shield itself after fixing ofthe module 40.

After assembly of the shield 90, the module 40 can be fixed in positionvia the elastic element 60, as may be seen in FIG. 68, and then thecircuit 15 is positioned in the corresponding seats 22, and theconnection is made via the electric wires 50 ₁, as may be seen in FIG.69. Advantageously, the wires 50 ₁ can be welded to the module 40 priorto fixing of the wires to the body 10 a, and/or the terminals 50 couldcomprise electrical connections of a snap-in type and/or of theinsulation-piercing type.

The assembled condition is clearly visible in the sections presented inFIGS. 70 and 71. In particular, from FIG. 70 it should be noted how thelower projections 46 b and 47 b of the bodies 46 and 47 are inserted inrespective positioning seats 37 and/or bear upon corresponding contrastelements in order to guarantee precise positioning of the bodies 46 ₂and 47 ₂, and hence of the emitter 42 and of the photodetectors 44 a, 44b, with respect to the inclined surfaces 33 a and 34 a of the formation31. The precision of positioning is rendered possible thanks to theflexibility of the conductors 48, 49 that connect the bodies 46 ₂ and 47₂ to the central body 45. The module 40 is held in position thanks tothe spring 60, the tabbed hole of which engages with interference on theformation 51 and on the outside of the appendages 35, exerting a thruston the shield 90 and on the module 40. The shield 90 is positioned inthe ways described above, between the elements 21 a, 21 b (FIGS. 65-66)and the peripheral wall 20 of the cavity H, and is held in positionthanks to the arms 62 of the spring 60, which are engaged in theexternal seats 95 a of the appendages 95 of the shield (see FIG. 64). Asmay be appreciated, in the assembled condition, the appendages 95 of theshield come to perform the function of protection for the emitter 42 andthe photodetectors 44 a, 44 b.

Operation of the device of FIGS. 61-71, as regards detection of thequality of the liquid solution, is similar to that of the previousembodiments.

In embodiments so far described the sensor device according to theinvention has a casing of its own, including the body 10 a and of thecover 13. In other various embodiments, at least a part of this casingmay be defined by a different body, which belongs to a different elementor component to which the device is associated. Embodiments of this typeare described with reference to the example of FIGS. 72-78, where thesame reference numbers as those of the previous figures are used todesignate elements that are technically equivalent to the ones alreadydescribed. In the case illustrated, the device according to theinvention is coupled to a level sensor, but in other embodiments thedevice according to the invention could be mounted on, or at least inpart integrated in, a UDM device or component, or a heater of the typereferred to previously.

Represented in FIGS. 72-78 is an example in which the body or casing ofthe device according to the invention comprises at least one first bodyof a level sensor 110, such as the body designated by 110 a, and asecond body of an optical sensor or assembly, such as the bodydesignated by 10, which are associated to one another in a sealed way,preferably with interposition of at least one further body or of asealing element, and/or via soldering or gluing. Possibly, at least onefurther body or sealing element is overmoulded on at least one of thefirst body 110 a of a level sensor 110 and the second body 10 a of theoptical sensor or assembly 10.

In various embodiments, at least the aforesaid first body is made of athermoplastic polymer (e.g., HDPE) or a thermosetting polymer (e.g., anepoxy resin), whereas the aforesaid second body is made of athermoplastic polymer (e.g., PSU or COC); the aforesaid further body ispreferably made of an elastically compressible polymer.

In various embodiments, it is hence possible to produce an opticalassembly for measuring the concentration (or other characteristicquantity) of the liquid substance or solution as a component separateand independent of the body of a different functional device, which mayhere assumed as being a level sensor, to be preferably coupled in athrough seat of the latter. Alternatively, it is also possible toproduce an optical measuring device having a body that defines a portionperforming the functions of the housing and/or assembly part previouslydesignated by 12, having a through seat in which to house and/or fix adifferent version of the body of the level sensor or other device, oragain to provide a body of the optical assembly that defines a casing ofthe same type as the one previously designated by 14, in order toreceive at least the part of the circuit support 15, which isresponsible for measurement of level or of a different quantity (such asthe portion of the circuit board 15 designated hereinafter by 15 b).

In this way, an optical measuring device according to the invention maybe integrated, for example, in level-measurement devices and the like. Asubstantial advantage of this type of solution is that the materialsthat form the main body of the level sensor and the body of the opticaldevice according to the invention could be different: for example, forthe body of the optical device that defines the positioning site 30 atransparent material may be used, for example designed to obtain betteroptical characteristics, whereas for the body of the level sensor (orother device) a different material, including a non-transparent one, maybe used, for example designed to obtain better mechanicalcharacteristics. In various embodiments, the body of the optical deviceaccording to the invention is made of thermoplastic material, inparticular PSU, whereas the body of the different device is preferablymade of a thermosetting material or resin.

With reference, for example, to FIGS. 72-73, designated by 110 a is themain body of a level sensor 110 having a level-sensing part 111,designed to face and/or extend at least partially within a container,for example a tank 1. The body 110 a then includes a housing and/orassembly part 112, configured for being coupled in a sealed way to thetank, for example in an opening similar to the one designated by 6 inFIG. 1, possibly having a different, namely larger, diameter: in thisway, in the mounted condition, a part of the body 110 a, and especiallyits part 111, extends within the tank, substantially vertically, with abottom of the housing portion 112 that also faces the inside of thetank, in contact with the liquid substance. The housing and assemblypart 112 is preferably provided with a corresponding closing cover 113,having a shape similar to that of the cover 13, of appropriate diameter.

Preferably, the body 110 a is hollow for housing at least part of thelevel-sensing components, in particular the components of a level sensorof a capacitive type, as well as at least part of the components of adevice 10 according to the invention. In particular, the body 110 adefines, in a position corresponding to the sensing part 111, a hollowcasing 114, having a generally elongated shape. In the exampleillustrated, the casing 114 has a generally prismatic shape, inparticular substantially parallelepipedal. In preferred embodiments, thebody 110 a defines in a single piece of plastic material the housingpart 112 and the casing 114. There is not on the other hand ruled outthe possibility of providing the body 110 a in distinct parts renderedfixed in a sealed way, for example via mutual coupling means, or elsevia welding or overmoulding.

Once again in FIG. 72 it may be noted how the housing part 112 defines acavity, designated as a whole by H₁, which together with the cover 113delimits a housing for part of the electrical and electronic sensingcomponents. In a preferred embodiment at least part of these componentsis mounted on the circuit support 15, which has a shape different fromthe embodiments illustrated previously. In particular, identified in thecircuit support 15 of FIG. 72 are a first portion 15 a that is to bereceived in the housing part 112 and a second portion 15 b that is to bereceived in the casing 114.

Prevalently associated to the portion 15 a of the circuit support 15 arethe sensing and/or control electronic components, which are preferablyconnected both to the level sensor 110 and to the optical sensor device10 according to the invention. The aforesaid components preferentiallyinclude both the components for treatment and processing oflevel-sensing signals and the components for treatment and processing ofquality-sensing signals. The terminals 16 form, with a connector body113 a of the cover 113, an interface or connector for externalelectrical connection of the ensemble formed by the level sensor 110 andthe optical device 10, for example to a control unit of the system 2 onboard a vehicle. Associated to the portion 15 b of the circuit board 15is at least part of the components used for level sensing. In variousembodiments, the aforesaid components include a linear ortwo-dimensional array of electrodes, represented schematically by theblock designated by J, such as electrodes that extend in a directiontransverse to the axis of the portion 15 b, substantially from theproximal end to the distal end of the sensing part 11. Preferentially,level sensing is obtained by means of a measurement arrangement withoutmoving parts such as a float, in particular for reasons of reliability;for this purpose, in various embodiments, the level-measurementarrangement is obtained according to the technique described in any oneof the international patent applications Nos. PCT/IB2015/054020,PCT/IB2015/057036 and PCT/IB2015/057043, filed in the name of thepresent Applicant, the teachings of which in this regard areincorporated herein for reference.

In the example illustrated, a single circuit support 15 is provided,defined in which are the parts 15 a and 15 b, but in possible variantembodiments a number of circuit supports may be envisaged connectedtogether by means of suitable electrical-interconnection means andpossibly mechanical-interconnection means, for example a circuit supportcorresponding to the portion 15 a and a circuit support corresponding tothe portion 15 b, with electrical conductors or connectors forelectrically connecting electrically conductive paths of one portion toelectrically conductive paths of the other portion, or again a circuitsupport carrying part of the components just for detection of quality(or some other characteristic of the substance), connected to a circuitsupport carrying at least part of the components for level sensing.

In various embodiments, the housing and/or assembly part 112 of the body110 a includes a peripheral wall 120 and a bottom structure or wall 121,which define the cavity H₁ designed for housing electrical and/orelectronic components. Preferably, the peripheral wall 120—here having asubstantially cylindrical shape—has a flange 120 a for fixing the body110 a in position. With the device 10 in the mounted condition, at leasta part of the bottom structure or wall 121—and in particular its outerside—is to come into contact with the liquid solution contained in thetank. Defined in the bottom wall 121 is at least one opening or seat122, which connects the cavity H₁ to the inner cavity of the casing 114,which can house a sensing part of a level sensor (such as the part 15 bof the circuit support 15 carrying the electrodes J) or, in otherembodiments, a different sensor or an electrical heating device.

As has been said, the cover 113 includes or defines a generally hollowconnector casing 113 a, for housing the electrical terminals 16. Thecover 13 is designed for being fixed on the main body 110 a, inparticular on its housing and assembly part 112 so as to close thecavity H₁, preferably in a sealed way. In various embodiments, the cover113 defines for the purpose a flange 113 b for fixing to a flange 120 aof the part 112. Preferably, in at least one of the bodies 110 a and 113means are provided for fixing the level sensor (or other device) to thetank, such as perimetral holes, for example holes 120 b in the flange120 a and holes 113 d in one or more radial formations 113 c of theflange 113 b.

In various embodiments, the main body 110 a has a seat or a throughopening 121 c in its bottom wall 121, in a position corresponding towhich a device 10 according to the invention is to be mounted in asealed way.

The device 10 is visible in different views in FIGS. 74-75. The device10 has a respective main body 10 a made at least in part of a materialtransparent to light or to the operating optical radiation of theoptical sensor. The body 10 a has a peripheral wall 20, preferablydefining a flange portion 20 a, and a bottom wall 21 designed to beexposed to the substance contained in the tank 1. Preferentially,moreover, defined along the peripheral wall 20 is a seat 20 c for anannular sealing element, designated by 150 only in FIG. 76.

In various embodiments, in its upper part, in particular at itsperipheral wall, rising from the body 10 a are engagement elements 20 dfor being engaged at the opening 121 c of the body 110 a. The engagementelements 20 d may define a sealed fixing in combination with the sealingelement 150, or else may provide a provisional fixing during theproduction steps, final fixing and/or sealing being then obtained insome other way, for example via welding or gluing or resin bondingbetween the body 10 a and the body 110 a (e.g., laser or vibrationwelding, or welding by melting of the material of at least one betweenthe body 10 a and the body 110 a).

Present at the upper face of the body 10 a, i.e., at the inner side ofits wall 21, is the positioning site 30, including the optical formation31, on which an optical module 40 is to be mounted, the site, themodule, and the corresponding connections possibly being obtainedsubstantially according to any one of the embodiments described and/orillustrated previously. Connection to the circuit support 15 may beobtained via electric wires or an electrical connector, possibly of asnap-in type, or via appropriately shaped terminals 50.

In embodiments of this type, it is preferable for the separate spring(60, 60 ₁, 60 ₂) of the previous embodiments to be replaced by abridge-like element 60 ₃, which extends between opposite parts of theopening 121 c, fixed with respect to the wall 121 of the body 110 a orsecured thereto. With reference, for example, to FIG. 77, also theelement 60 ₃ hence includes a central part 61 provided with a hole 61 ahaving a profile congruent with the profile in plan view of theformation 51 and of the appendages 35. Extending from the central part61 are the two opposite arms 62.

As may be appreciated, the device 10 is obtained by providing the body10 a, in particular via moulding, preferably associated to which is thesealing element 150. The module 40 is fitted on its formation 31, withmodalities similar to the ones described previously, and the device 10is then mounted in a sealed way in the corresponding seat 121 c startingfrom the outer side of the bottom wall 121, in such a way that the teeth20 d engage on the inner side of the wall 121 itself, therebyguaranteeing a precise sealed coupling. Coupling between the bodies 10 aand 110 a could be of an elastic type following upon interposition ofthe sealing element 150, which enables in this case an elastic mountingof the device 10 with respect to a possible bridge-like element 60 ₃ ofa rigid type, such as a bridge-like element made of a single piece withthe body 110 a.

Positioning of the device 10 is carried out by making sure that theformation 51 of the module 40 and the respective projecting parts of theappendages 35 of the formation 31 are fitted in the central hole 61 a ofthe bridge-like element 60 ₃. In the mounted condition, as may be seenin FIG. 77, the arms 62 of the element 60 ₃ engage the seats 46 a and 47a (FIG. 76) provided on the outer side of the bodies 46 and 47 andposition and/or force the bodies themselves elastically into theircorresponding position of contact against the contrast elements: in thisway, precise positioning of the emitter 42 and of the photodetectors 44a, 44 b with respect to the inclined surfaces of the formation 31 isguaranteed. Next, the connection to the circuit support 15 is made, forexample, via the electric wires 50 ₁, as may be seen in FIG. 78.

It should be noted that, according to further possible embodiments ofthe invention, it is also possible to provide a body of the opticalassembly, for example a body of the type designated previously by 10 a,and subsequently overmould thereon a body of a different device orsensor, for example a body of the type designated previously by 110 a,or, vice versa, to overmould the body of the optical assembly on thebody of the other device or sensor. Of course, an embodiment of thistype, i.e., with overmoulding of a body of the sensor device on a bodyof the optical sensor, may be implemented in all the embodiments of theinvention that are described and/or illustrated in the presentapplication.

As may be appreciated, in various embodiments—such as the one of FIGS.72-78—an optical sensor device according to the invention and adifferent sensor (such as a level sensor and possibly also at least onetemperature sensor) and/or a different device or component have anelectrical connector in common, here represented by the connector 113 a,16. Likewise, the device forming the subject of the invention and atleast a further device or component, or a further sensing arrangement,or a different sensor, such as a level-sensing arrangement and/ortemperature-sensing arrangement, may share part of one and the samecircuit arrangement, and especially at least its electronic controllerMP, which will hence be configured for managing operation of theplurality of different sensors and/or devices. Likewise, preferentially,one and the same circuit—here represented by the circuit support15—determines at least part of the connections of the optical sensorand/or an emitter and a receiver of the optical sensor and of thesensing and/or control means of at least one further sensor, such as alevel sensor and/or a temperature sensor.

According to possible embodiments, the site 30, and in particular itsformation 31, may be provided with a diffraction grating on an opticalsurface thereof, in particular the inclined surface 33 a.

In these embodiments, the operating principle of the optical sensorremains unaltered, being based once again on the variation of thecritical angle as a function of the concentration of the liquidsolution. The modification, which may be applied to all the embodimentsdescribed herein, consists in inserting a diffraction grating at theoptical surface 33 a facing the emitter, i.e., with reference to FIG.79, in the area designated by 107, preferably an inclined area orsurface. The basic structure remains in any case unvaried with respectto what has been described so far.

The diffraction grating 107, in the presence of an incidentmonochromatic light beam, gives rise to a transmitted beam and tovarious diffracted beams, with a diffraction angle that depends upon theratio between the distance between the rows of the grating 107 and thewavelength of the incident light. Given the same grating 107, light witha longer wavelength is deflected at an angle wider than that of thedirection of the incident ray. By means of the diffraction grating 107,the incident ray is hence decomposed into various light rays referred toas diffraction order or mode.

The diffraction grating 107 is obtained by providing on the opticalsurface 33 a, i.e., on the side facing the emitter 42, an orderlyalternation of recesses and/or reliefs, which give rise to a sort ofcrenalation or a series of furrows, preferably parallel to one another,as represented schematically in FIG. 80 (at least some reliefs and/orrecesses could possibly extend also in different directions or at leastin part cross one another). Of course, the pitch of the grating, i.e.,dimensions and distance between the recesses and/or reliefs, must bechosen according to what has just been explained above.

By decomposing the monochromatic ray emitted by the emitter, diffractedrays will be generated that will impinge upon the liquid/solid interfacesurface—i.e., the outer surface 21 ₁ of the wall 21 between the twoparts 33, 34 of the formation 31 (FIG. 79)—at different angles, greaterand smaller than the critical angle. The diffracted rays that impinge atan angle of incidence greater than the critical angle upon the interfacesurface 21 ₁ will be totally reflected, whereas the rays with a smallerangle of incidence will always be partially reflected and partiallyrefracted. As the concentration of the liquid solution varies, asexplained previously, the critical angle will change, and consequentlyalso the intensity of the light rays on the two photodetectors 44 a, 44b. The electrical signal generated by the two photodetectors will hencechange as a function of the concentration, and by measuring thevariation of the signals of the two photodetectors it will be possibleto measure the variation of concentration.

In embodiments of this type it is preferable for the emitter 42 to be ofa concentrated, i.e., collimated, type, with a divergence of theemission limited to a few degrees, preferably less than 3° (in theembodiments that do not envisage the grating 107 it is not necessary forthe emitter 42 to be of a collimated type). The space filter 43 is inany case preferably used for collimating more the light emissiongenerated on the diffraction grating 107. In the case where the emitter42 is of a monochromatic type, the diffracted rays will always be of amonochromatic type, and hence also the photodetectors 44 a, 44 b willhave to be sensitive to the same monochromatic rays as those of thesource (i.e., with a specific wavelength).

Instead, if the emitter 42 is of a polychromatic type, the diffractiongrating 107 enables separation also of the light rays in terms ofwavelength (i.e., into the various colours): considering the operatingprinciple, the two photodetectors 44 a, 44 b will receive rays withdifferent wavelengths, and consequently they will have to be sensitiveto light rays of different wavelengths. Alternatively, it is possible touse a number of diffraction gratings 107 with different pitches,designed so as to direct the light always onto the two photodetectors,with a number of emitters 42 at different wavelengths. In theseembodiments, the emitters 42 are turned on at different times, and theresulting signals are acquired using always the same photodetectors.

It is in any case preferable to use a monochromatic light source 42 toprevent introduction of variation of the refractive index (and hence ofthe critical angle) also as a function of the wavelength and not only asa function of the concentration of the liquid solution.

As regards the diffraction grating 107, various shapes are obviouslypossible, in order to obtain the desired effect, including shapes thatare different from the ones exemplified. The profiles of the grating 107may be obtained via mechanical etching or else with holographictechniques or, preferably, with micromachining techniques borrowed frommicroelectronics, or else with micro-moulding techniques. In particular,the solution in which the diffraction grating 107 is moulded of a singlepiece together with the formation 31 (i.e., with the body 10 a or thebody 101) is preferable. In this case, the mould used may be of amodular type, i.e., with an insert appropriately micro-structuredsuperficially, at the point where the grating 107 is to be defined.

In various embodiments, the device according to the invention isequipped with an optical sensor for detecting the quality or othercharacteristics of the substance, the operating principle of which isbased upon inner reflection or on the use of an optical waveguide.Embodiments of this sort are described with reference to FIGS. 81-88 and89-97, where the same reference numbers as those of the previous figuresare used to designate elements that are technically equivalent to theones already described above.

As is known, considering a light source that illuminates the input of anoptical fibre, the discontinuity of the refractive index between thematerials of the core and of the cladding of the fibre traps the opticalradiation as long as this maintains a sufficiently grazing angle that iscontained within the cone of acceptance. In practice, to functionproperly according to total reflection, the fibre must not presentcurves that are excessively sharp. The principle of total innerreflection can be exploited for a measurement of characteristics orconcentration, by considering once again the difference in therefractive index between two media—i.e., the plastic material of thebody 10 a or 101 and the liquid substance or solution in contact withthe body—and the variation of this index as a function of theconcentration of the substance or solution.

With initial reference to FIG. 81, in various embodiments, at the innerside of the wall 21 of the body 10 a a positioning site 30 ₁ is defined,which is shaped differently from the previous embodiments and includes aseat 31 ₁ for an optical module 40 ₁, which also has a structuredifferent from that of the embodiments so far described. In the exampleillustrated, and as is clearly visible in FIG. 82, the supportingstructure of the module 40 ₁ comprises a substantially plate-like body41 ₁, associated to the underside of which are an emitter 42 and areceiver 44, here consisting of a single photodetector. The body 41 ₁may be advantageously constituted by a printed circuit support, such asa PCB, on which there are provided paths of electrically conductivematerial 48 ₁, 49 ₁ for electrical connection of the electroniccomponents 42 and 44. The circuit support 41 ₁ has respective connectionelements 50 ₃, connected to the aforesaid paths, for example in the formof solder pads and/or metallized through holes, for electricalconnection of the module 40 ₁. Also in this case, preferentiallyassociated to the emitter 42 is a corresponding space filter 43 of thetype described previously. According to possible alternative embodiments(not represented), also the circuit support 41 ₁ may be obtained with atechnique similar to the one described in relation to the previousembodiments; i.e., it may comprise a body made of an electricallyinsulating material, for example a plastic material, overmoulded onelectrical-connection elements may of electrically conductive material,which perform the functions of the paths 48 ₁, 49 ₁ and of theconnection elements 50 ₃, hence using a technique similar to the onedescribed in relation to previous embodiments.

In the example, the circuit support 41 ₁ has a substantiallyquadrangular shape, and the seat 31 ₁ defined on the inner side of thewall 21 is shaped accordingly, to receive inside it at least part of thecircuit support 41 ₁, with the emitter 42 and the receiver 44 facing thewall 21. Obviously possible are other shapes for the seat 31 ₁ and forthe circuit support 41 ₁. Preferably, the wall 21 likewise definescontrast elements for resting of the circuit support 41 ₁ within theseat 31 ₁, one of these contrast elements being designated by 37 ₁ inFIG. 81. On the other end, at the outer side of the wall 21, the body 10a defines or comprises an optical guide, designed to diffuse the lightor optical radiation emitted by the emitter 42 as far as the receiver44. This guide, designated by 31 ₂ in FIG. 83, preferentially has agenerally U-shaped configuration, the two ends of which are located atthe area that, on the inner side of the wall 21, is circumscribed by theseat 31 ₁. The optical guide 31 ₂ may be integrated in the body 10 a,for example moulded in a single piece, in particular made of a materialpermeable to an emitted optical radiation or light. Alternatively, theoptical guide 31 ₂ may be mounted in the body 10 a; for example, it maybe associated to a body of its own of a type similar to the body 10 a ofFIGS. 72-78, which is preferably made of a plastic material that ispermeable to optical radiation or light, is moulded separately and thenmounted on the body 10 a, or else is overmoulded on the body 10 a, withthe latter that may be made of a material of a different type, such as aplastic material not permeable to optical radiation or light.

The optical guide 31 ₂ is preferably massive, i.e., full, and is made ofthe material suitable for diffusion of optical radiation, as explainedpreviously, to perform substantially the functions of an optical-fibrecore: as will be seen, the functions of the cladding of this fibre areinstead performed by the liquid solution contained in the tank, in whichthe guide 31 ₂ is immersed.

The module 40 ₁ is preferably slotted into the corresponding seat 31 ₁,as may be seen in FIG. 84, in order to have a precise assembly of theemitter 42 and receiver 44 components with respect to the two ends ofthe guide 31 ₂. In preferred embodiments, in order to render assembly ofthe module 40 ₁ more rigid and sturdy, it is possible to envisage aresin bonding and/or gluing thereof in its seat 31 ₁.

Also in embodiments of this type, the circuit 15 is inserted in itsseats 22, as represented schematically in FIG. 84, with the circuititself that remains within the cavity of the body 10 a. There can thenbe made the electrical connection of the module 40 ₁ using electricwires 50 ₁ or other terminals, connected to the holes or pads 53 or thelike provided in the circuit 15, as may be seen in FIG. 85.

As may be seen in FIG. 86, in the configuration where the module 40 ₁ isassembled, the emitter 42 and the receiver 44 are set facing each arespective end of the optical guide 31 ₂, which, in the mountedcondition of the device 1, is immersed in the liquid solution (it is tobe recalled that, in the actual configuration of use, the device 10 ispreferentially set in a position turned upside down through 180° withrespect to what is illustrated in the figure). As mentioned, preferablyassociated to the emitter 42 is a space filter 43, for improvingconcentration of the optical radiation emitted and getting it to fallwithin the cone of acceptance of the guide 31 ₁.

In operation, the emitter 42 emits light in front of the first end ofthe guide 31 ₂, which, as has been said, is preferably integrated in thebody 10 a, i.e., made of a single piece therewith, and is immersed inthe solution the concentration of which is to be measured, whichperforms functions of cladding. Located in front of the opposite end ofthe guide 31 ₂ is the receiver 44, designed to capture the light beamemitted by the emitter 42 that has propagated within the plastic body ofthe guide by exploiting inner reflection.

FIGS. 87 and 88 exemplify two situations with a liquid solution at twodifferent concentrations. In the case of FIG. 87, the solution has afirst concentration Conc 1 such that the critical angle is smaller thanthe angle of incidence of the ray R emitted by the emitter 42. The ray Ris hence totally reflected, reaching the receiver 44 with a certainintensity. Consequently, assigned to the value of concentration Conc 1is a certain value of the signal at output from the receiver 44. FIG. 88highlights, instead, the case where the liquid solution has aconcentration Conc 2 that is greater than Conc 1. In this case, thecritical angle increases, and the ray R incident on the surface ofinterface between the material of the guide 31 ₂ and the liquid, at thesame angle, will be partially reflected and partially refracted, as isexemplified in FIG. 88. There will follow various reflections andrefractions each time that the ray reflected in the previous stepimpinges upon the interface surface. Consequently, the ray R will reachthe receiver 44 with a certain attenuation, caused by partialreflection/refraction, i.e., with an intensity lower than in theprevious case corresponding to the concentration Conc 1 of FIG. 87. Thesignal emitted at output from the receiver 44 will hence be differentfrom the previous case, thus enabling discrimination of the value ofconcentration. Considering the transimpedence, the gain, and theresponse of the receiver 44, a signal A will be obtained that varies asa function of the intensity P incident on the receiver, and consequentlyas a function of the concentration of the fluid, as has already been setforth previously:

A=ka*P·response*transimpedance

The intensity P incident on the receiver 44 will be given by thecombination of all the rays emitted by the emitter 42 within the cone ofemission, totally and partially reflected in the guide 31 ₂. Thepartially reflected rays will hence have an intensity that decreases ateach reflection: if the intensity P is not sufficiently high, these rayscould even vanish and not reach the receiver 44.

As has been said, the measurement is based upon a detection ofintensity: the receiver 44 changes its output signal on the basis of thevariation of the incident light intensity, which is in turn a functionof the concentration of the liquid solution.

With embodiments of the type referred to, the quality-measurement systemis sensitive to the variation of operation of the emitter 42 and to thevariation of the characteristics of the plastic material thatconstitutes the wall 21 and the guide 31 ₂, which are principally causedby ageing and temperature variations. These factors could alter thelight intensity of the ray emitted (ageing of the source) or else theoptical properties of the plastic material (refractive index andconsequently critical angle), thus causing errors of measurement.

Consequently, according to particularly advantageous embodiments, anadditional or auxiliary emitter and an additional or auxiliary receiverare provided, preferably facing one another, with interposition of atleast one reference optical element or waveguide not immersed in thefluid to be detected; this reference optical guide is preferentially,located in the cavity H and/or at the inner side of the wall 21.Preferably, the aforesaid reference optical element or guide is made ofthe same material as the sensing optical guide 31 ₂ and/or as the wall21 and/or as the body 10 a (or 101). In the case exemplified in FIG. 85,the additional emitter and receiver—designated by 42 ₁ and 44 ₁,respectively—are set at the two opposite ends of a formation 37 ₂, whichis preferentially defined in a space comprised between the seat 31 ₁ andthe seats 22, with this formation that hence provides the aforesaidreference optical element or guide. The aforesaid reference opticalguide may, however, be configured as an independent element, mountedbetween the emitter 42 ₁ and the receiver 44 ₁, or again be defined byone of the walls of the seat 31 ₁, for example the rear wall closer tothe seats 22.

In the example illustrated, the emitter 42 ₁ and the receiver 44 ₁ aremounted on the circuit support 15 (see FIG. 84) in an area such that,following upon complete insertion of the circuit board itself in thecorresponding seats 22, they will be set facing the two ends of theformation 37 ₂.

The ray emitted by the emitter 42 ₁ and consequently received by thereceiver 44 ₁ is not involved in any possible refraction/reflection withthe liquid solution, in so far as the ray remains prevalently confinedwithin the body 10 a, and precisely within its formation 37 ₂. Theelectronic components 42 ₁ and 44 ₁ are of the same family, in terms ofcharacteristics, as the electronic components 42 and 44 used formeasuring concentration. In this way, via the aforesaid additionalcomponents, it is possible to have a reference on the light intensityemitted to be used for a normalized measurement and compensate thevariations of intensity produced by ageing and/or environmentalvariations of the material of the body 10 a and/or of the referenceoptical guide 37 ₂ and/or of the sensing optical guide 31 ₂. Thisreference is constituted by the signal emitted by the receiver 44 ₁,which will be used by the control electronics for making the necessarycompensation of the signal emitted by the receiver 44.

It should be noted that, as described with reference to FIGS. 72-78, themodule 40 ₁, the seat 31 ₁, and the light guide 31 ₂, and possibly alsothe reference optical guide 37 ₂ and/or the corresponding emitter 42 ₁and receiver 44 ₁, could belong to a distinct unit, which may bepositioned in a sealed way at a corresponding through opening of adifferent device or component, such as a level sensor or a differentsensor or a UDM component or a heater device.

In various embodiments, the electronic components 42 and 44 used for themeasurement and the similar components 42 ₁ and 44 ₁ used for correctingthe measurement made may also be integrated in one and the same opticalmodule. Variant embodiments of this type are described with reference toFIGS. 89-97, where the same reference numbers as those of the previousfigures are used to designate elements that are technically equivalentto the ones already described.

With initial reference to FIGS. 89-90, designated by 40 ₂ is an opticalmodule of the type referred to above, i.e., comprising the components42, 44 and 42 ₁, 44 ₁, which is designed to be mounted at a positioningsite 30 ₂ defined on the wall 21 of the body 10 a. The site 30 ₂includes a formation 31 ₃, which comprises at least two mounted parts orappendages 35 that are generally parallel, functionally similar to theappendages 35 of embodiments described previously. The formation 31 ₃ islocated within a seat 31 ₄ defined in the bottom wall 21. In theexample, the aforesaid seat is substantially C-shaped and is defined bya larger wall and two side walls that project from the inner side of thewall 21. Likewise projecting from the wall 21 is a further wall 31 ₅,here generally parallel to the larger wall of the seat 31 ₄, which inthe assembled condition of the module 40 ₂, is designed to be setbetween the auxiliary emitter and the auxiliary receiver, as clarifiedhereinafter. The module 40 ₂ is designed to be secured on the formation31 ₃ by way of a generally ring-shaped blocking and/or positioningelement 60 ₄, provided with a central tabbed hole. In variousembodiments, the module 40 ₂ is electrically connected to the circuitsupport 15 with modalities similar to the ones described with referenceto FIGS. 2-26, i.e., exploiting elastically flexible terminals of themodule itself, or else connected with wires or in other ways asdescribed previously.

A possible embodiment of the module 40 ₂ and its structure 41 ₂ isillustrated in FIGS. 91-93. The load-bearing structure 41 ₂ of themodule 40 ₂ basically consists of a substantially C-shaped body made ofplastic material, i.e., comprising a central upper wall 45 ₃ and twoside walls 46 ₃ and 47 ₃, generally orthogonal to the central wall, atits two ends, or possibly walls 46 ₃ and 47 ₃ inclined with respect tothe central wall 45 ₃. This body is overmoulded on connection terminals50, functionally similar to the terminals 50 of FIGS. 2-26, preferablyat least in part elastically flexible, designed for connection to thecircuit 15. The body of the structure 41 ₂ is likewise overmoulded onconductors 48 ₂ and 49 ₂—which are in part accessible at the undersideof the wall 45 ₃—for electrical connection of the emitter 42 and of thereceiver 44, respectively, as well as to terminals that are in partaccessible at the outer side of the walls 46 ₃ and 47 ₃, for connectionof the auxiliary emitter 42 ₁ and of the auxiliary receiver 44 ₁ (inFIG. 91, one of the conductors for the emitter 42 ₁ is designated by 48₄, the conductors for connection of the receiver 44 ₁ having asubstantially similar arrangement).

Provided at the upper face of the central wall 45 ₃ is a formation 51with the corresponding through openings 51 a, whereas provided at thelower face of the same wall is a formation 52 with the correspondingwall 52 a, as in various embodiments described previously. The auxiliaryelectronic components 42 ₁ and 44 ₁ are mounted on the outer side of thewalls 46 ₃ and 47 ₃, which are purposely provided with through holes 46_(3a) and 47 _(3a), the hole 46 _(3a) provided for the emitter 41 ₁basically performing the functions of space filter. The electroniccomponents 42 and 44 are mounted on the inner side of the wall 45 ₃.Preferably associated to the emitter 42 is a corresponding space filter,for example of the type previously designated by 43.

Preferably, moreover, the upper face of the central wall 45 ₃ has twopositioning projections 51 ₁ for the blocking element 60 ₄, the profileof which defines recesses that are able to engage with the aforesaidprojections 51 ₁.

As may be noted, as compared to the version of FIGS. 81-88, theauxiliary emitter 42 ₁ and the auxiliary receiver 44 ₁, provided forcompensating ageing of the emitter 42 and of the plastic material of thebody 10 a, are mounted on the module 40 ₂, which also carries the mainsensing emitter 42 and the main sensing receiver 44.

In the case exemplified, the module 40 ₂ is connected to the circuit 15,preferably by way of the flexible terminals 50, it being possible,however, to use other connections, also of a rigid type. The blockingelement 60 ₄ may be pre-assembled on the upper formation 51 of themodule 40 ₂, also exploiting the corresponding positioning projection 51₁. The circuit is then inserted in the seats 22, as representedschematically in FIG. 94 until the module 40 ₂ comes to rest on the seat31 ₄, as represented schematically in FIGS. 95 and 96. In this step, thetwo appendages 35 of the formation 31 ₃ penetrate into the throughopenings 51 a, and the wall 52 a of the lower formation 52 of the modulepenetrates between the two appendages (see FIG. 96), with some tabs ofthe central hole of the blocking element 60 ₄ that apply the necessarygrip on the outer sides of the appendages 35.

In the condition thus assembled, as may be seen also in FIG. 97, setbetween the emitter 42 ₁ and the receiver 44 ₁ is the wall 31 ₅ (orother appropriately shaped wall): the ray generated by the emitter 42 ₁reaches the receiver 44 ₁ passing through the wall 31 ₅, thus givingrise to a reference signal.

In this way, as has already been described previously, it is possible tohave a reference for compensating possible variations of light intensitydue to ageing of the main emitter 42. As has been said, in fact, theemitters 42 and 42 ₁ are of the same family. Furthermore, thanks to thepresence of the wall 31 ₅, the ray incident on the receiver 44 ₁ is afunction of the refraction introduced by the plastic material of thebody 10 a. In this way, as described with reference to FIGS. 81-89, thevariation of the refractive index due to ageing of the plastic materialentails a variation of the intensity of the refracted light ray andhence a variation of the light intensity on the receiver 44 ₁, i.e., ofthe signal emitted by the latter. Considering, then, the signal of theauxiliary receiver 44 ₁ as reference, it is possible to compensate thevariation of the properties of the material and/or alterations due toother environmental factors or conditions of use.

Exemplified in FIG. 98 is a possible electrical diagram of the module 40₂, for its connection to a corresponding interface circuit, hererepresented by the circuit support 15 of the level-sensing device 10. Asmay be noted, the terminals 50 preferably make it possible to have asinput and output signals a supply level Vcc of the emitter 42 and of theemitter 42 ₁, a ground GND, and two voltage signals A and Ccorresponding to the two photodetectors 44 and 44 ₁. These signals A andC are sent to the circuit support 15 for numeric processing within thecontroller MP (as also represented schematically in FIG. 99) and/or sentto an external circuit via the electrical connector 13 a, 16 (or 113 a,16).

Exemplified, instead, in FIG. 99 is a block diagram of operation of thequality optical sensor that includes the module 40 ₂. In this figure,designated by Vcc is the low-voltage supply of the emitters 42 and 42 ₁,the block OG represents the optical geometry defined by the guide 31 ₁and the corresponding part of wall 21, and the block OR represents thepart 31 ₅ of the body 10 a set between the emitter 42 ₁ and the receiver44 ₁. As may be noted, the voltage signals A and C at output from thereceivers 44 and 44 ₁ are treated by a conditioning circuit CC, and theconditioned signals A1 and C1 reach corresponding inputs of themicroprocessor MP, which—by correcting the signal A1 as a function ofthe signal C1—generates the signal S representing the value ofconcentration of the solution or of some other characteristic or thetype of the substance. Also in this case, the components CC and MP arepreferably located on the circuit board 15, with the microcontroller MPthat manages both level sensing and quality sensing of the liquidsolution. The block diagram of FIG. 99 of course also applies inrelation to the embodiments described with reference to FIGS. 81-88.

Also general operation of the quality optical sensor of FIGS. 89-99 issimilar to what has been described with reference to FIGS. 81-88, inparticular as regards use of the emitter 41 and of the receiver 44 incombination with the light guide 31 ₂ (see in particular, the part ofdescription regarding FIGS. 87-88).

Obviously, each one from among the site 30 ₂, the formation 31 ₃, theseat 31 ₄, and the wall 31 ₅ could have a shape different from the oneexemplified, provided that their functions are maintained, and insteadof the flexible terminals 50 electric wires could be used of the typepreviously designated by 50 ₁.

In various embodiments, the optical sensor that equips the device 10according to the invention bases at least in part its operation on thelaws of optical refraction, and in particular on refraction of a lightray in its passage from a solid to a fluid (two media with refractiveindices different from one another) and on the variation of therefractive index with the concentration of the fluid. As is known fromphysics and from Snell's equations, given the same angle of incidence ofthe incident ray, the variation of the refractive index of thefluid—which is representative of its concentration, as already explainedabove—entails a variation in the angle of the ray refracted through thefluid. By adequately pre-arranging an element for receiving opticalradiation, it is thus possible to detect the position of incidence ofthe refracted ray and hence measure the concentration and/orcharacteristics of the fluid.

Embodiments of this type are described with reference to FIGS. 100-111,where the same reference numbers as those of the previous figures areused to designate elements that are technically equivalent to the onesalready described.

With initial reference to FIG. 100, in embodiments of this type apositioning site 30 ₃ is provided, which includes a formation 210 thatrises from the wall 21 towards the inside of the cavity H of the body 10a. The formation 210 comprises a shaped wall that, preferably but notnecessarily, extends through the cavity H and has at the top positioningelements for an optical module 40 ₃. In the example, this module 40 ₃ isdesigned to rest on the upper surface of the formation 210, whichpreferentially defines at least one upper appendage 210 a and, verypreferably, lateral contrast elements 210 b for the module 40 ₃, as maybe seen in FIGS. 105 and 106.

In embodiments of this type, it is envisaged to use a shaped opticalinsert for propagation of a light ray, designated as a whole by 220,made at least in part of transparent material or material permeable tooperating optical radiation of the sensor, for example, the samematerial as that of the wall 21. The optical insert 220 is designed tobe housed in a corresponding seat, designated by 230, basicallyconsisting of a portion of the bottom wall 21, which is shaped so as todefine a cavity projecting from the main plane of the wall itself, as isclearly visible in FIG. 101. As may be noted in this FIG. 101, theportion defining the seat 230, which is to be immersed in the liquidsolution, includes two outer surfaces 230 a, 230 b that are angled withrespect to one another. In the example, the two surfaces 230 a and 230 bform between them an angle greater than 90°.

The insert 220 is represented in different views in FIGS. 102 and 103,preferably moulded and/or made of a plastic material. The body of theinsert 220 has a main wall 221, which is preferably plane and providedwith a through hole 221 a designed for coupling with the appendage 210 aof the formation 210. Preferentially projecting on the upper side of thewall 221 is an appendage 221 b for positioning of the optical module 40₃.

On the underside of the wall 221 there project two elements fortransmission of light 222 and 223, each of which has, at the distal end,an inclined surface 222 a and 223 a, preferably inclined at about 45°.Preferably, moreover, the body of the insert 220 likewise defines twohousings or seats 222 b and 223 b, which open at the upper side of thewall 221, each in a position corresponding to a respective transmissionelement 222 and 223. The body of the insert is preferably made of asingle piece, including the transmission elements 222 and 223. As willbe seen, the seats 222 b and 223 b are designed to house at leastpartially an emitter and a receiver of the optical module 40 ₃.Preferentially, the transmission element 223 has an elongated crosssection, for example substantially rectangular, given that thecorresponding inclined surface 223 a is designed to receive an incidentlight ray, the position of which may vary—in the longitudinal directionof the surface 223 a—as a function of the concentration of the liquidsolution. The transmission element 222 has in the example a circularcross section.

The seat 230 (FIGS. 100-101) is designed to receive inside it at leastpart of the transmission elements 222 and 223 and is hence shapedaccordingly and/or has an at least in part complementary shape,preferably with at least some inner walls of the seat 230 set facing orcoupled to at least some surfaces of the transmission elements 222 and223.

With reference to FIG. 104, the optical module 40 ₃ has a structure 41 ₃that comprises a substantially plate-like supporting body, preferablyconstituted by a printed circuit support or PCB, which has two throughopenings 41 _(3a) and 41 _(3b), for the appendage 210 a of the formation210 and the appendage 221 b of the insert 220, respectively.

Associated to the underside of the structure 41 ₃ are at least oneemitter 42 ₂ and at least one receiver 44 ₂ of optical radiation,preferably visible radiation. The emitter 42 ₂ may for example be alight-emitting diode. In preferred embodiments, the receiver 44 ₂ is areceiver of the CMOS-array type, comprising a linear or two-dimensionalarray of independent pixels each constituted by a photodetector. Thestructure 41 ₃ includes suitable elements for electrical connection ofthe components 42 ₂ and 44 ₂, not illustrated for reasons of clarity,which comprise, for example, paths made of electrically conductivematerial and metallized holes for the terminals of the aforementionedcomponents. According to possible alternative embodiments (notrepresented), also the structure 41 ₃ may comprise a body made of anelectrically insulating material, for example a plastic material,overmoulded on electrical-connection elements made of electricallyconductive material, which perform the functions of the aforesaid pathsand holes, i.e., using a technique similar to the one described inrelation to previous embodiments.

In preferred embodiments, the electrical connection between the module40 ₃ and the circuit support 15 of the device is obtained by way of aflat cable designated by 50 ₄, for example, in FIGS. 100-101, in whichcase the circuit 15 will be preferably equipped with a connector orpaths and/or conductive pads for connection. Obviously, it is alsopossible to provide a connection via separate flexible terminals orelectric wires or with other connections, according to what has alreadybeen described previously. Of course, a flat cable may also be used forconnection of the optical modules of various embodiments describedpreviously.

For the purposes of assembly, the optical insert 220 is mounted on thebody 10 a, as represented schematically in FIG. 105, in particular insuch a way that the underside of its wall 221 comes to rest on the uppersurface of the formation 230. In this step, care must be taken to seethat the hole 221 a of the insert 220 is fitted on the appendage 210 aof the formation 210. In the mounted condition, as may be seen in FIG.106, the upper contrast elements of the formation 210 contribute toproper positioning of the insert 220. In this condition, moreover, theelements 222 and 223 of the insert are inserted in the correspondingseat 230, in particular with the inclined surface 222 a of the element222 in a position opposite to the outer surface 230 b of the seat 230(see FIGS. 101 and 109) and the inclined surface 223 a of the element223 in a position opposite to the outer surface 230 a of the seat 230(see FIGS. 101 and 111).

Next, the circuit support 15 with the module 40 ₃ pre-assembled isinserted in the cavity of the body 10 a until the module itself comes torest on the upper side of the insert 220. For the purposes ofpositioning also the holes 41 _(3a) and 41 _(3b) of the structure of theoptical module are coupled to the appendage 210 a of the formation 210and the appendage 221 b of the insert 220, respectively, as may be seenin FIG. 107. In this condition, moreover, the emitter 42 ₂ and thereceiver 44 ₂ are positioned and/or at least partially housed within thecorresponding seats 222 b and 223 b of the insert 220 (see FIGS. 109 and111).

At this point, the module is fixed in position via a fixing ringsubstantially of the type already designated by 60 ₄, the tabbed hole ofwhich engages with interference on the appendage 210 a. The ring 60 ₄preferably operates also as spring, enabling positioning of the module40 ₃ and the optical insert 220 and/or recovery of possible assemblytolerances. The cover 13 is then fixed on the body 10 a, taking carethat the circuit couples to the respective seats 13 f (FIG. 101) of thecover itself.

As may be appreciated, at least the appendage 210 a and the hole 221 aprovide means for positioning and centring of the insert 220 withrespect to the formation 210, in combination with the possible contrastelements 210 b, whereas the appendage 210 a itself and the appendage 221b of the insert 220, with the holes 41 _(3a) and 41 _(3b) providepositioning and centring means for the module 40 ₃ with respect to theformation 210 and to the insert 220.

The insert 220 is designed to propagate the light ray generated by theemitter 42 ₂ as far as the receiver 44 ₂ also through the body 10 a, inparticular through the walls 230 a and 230 b of the corresponding seat230, and also through the liquid substance in which the walls areimmersed. The optical surfaces 222 a and 223 a of the insert are hencedesigned for reflecting the light ray in a correct way, also consideringthe interface between the air and the plastic material. Likewise, theseat 230, and in particular its outer surfaces 230 a and 230 b aredesigned for the purpose in order to refract the optical ray at theinterface between the plastic material and the liquid solution.

Operation of the optical sensor is exemplified in FIGS. 109-111. Withinitial reference to FIG. 109, the light ray R is emitted by the emitter42 ₂ within the insert 220, in particular within its element 222, untilit impinges upon its optical surface 222 a inclined at 45°, whichrepresents an interface between the solid and the air. For this purpose,the emitter 42 ₂ is preferably of a collimated type, to obtain a highlyconcentrated emission in the direction of interest.

The optical surface 222 a is preferably designed and inclined forbringing about a total reflection at the interface between the solid andthe air, with an outgoing ray R1 at 90° with respect to the incident rayR. The interface surfaces between the element 222 and the correspondingpart of the seat 230 are parallel to one another and orthogonal to theincident ray R1, and are provided with an appropriate surface finish.The ray R1 propagates without changing direction, neglecting the minorrefraction that is generated by the small distance between the insert220 and the seat 230.

With reference now to FIG. 110, the ray R1 then impinges upon theoptical surface of interface between the seat 230 and the liquidsolution, this surface being represented by the outer surface 230 b ofthe seat 230. The optical surface 230 b is designed and inclined in sucha way that the ray R1 is refracted in the ray R2 within the liquid,towards the other optical surface of interface between the liquid andthe seat 230, represented by the outer surface 230 a of the seat 230.When the incident ray R2 reaches the second interface surface 230 a, asa result of refraction it is transformed into the ray R3 through thecorresponding wall of the seat 230.

Also considering FIG. 111, the ray R3 passes from the inside of the seat230 to the insert 220, and in particular to its element 223. The twointerface surfaces, namely the interface between the plastic material(seat 230) and the air and the interface between the air and the plasticmaterial (element 223), are parallel to one another and orthogonal tothe incident ray R3 so that the ray does not undergo any deflection,once again assuming the small distance in air as being negligible. Theray R3 impinges upon the optical surface 223 a inclined at 45° of theelement 223, being transformed into the ray R4 that is totally reflectedtowards the receiver 44 _(a).

The ray R4 impinges upon the linear or two-dimensional array of thereceiver 44 ₂ and will light up a given pixel: in this way, to a givenconcentration Conc 1 of the liquid solution there will be associated agiven pixel lit up, and hence a signal generated by the receiver 44 ₂.In the case where the ray R4 lights up a number of neighbouring pixels,it will be possible to process the signal to define a corresponding meanpixel or mean point; alternatively, a different light intensityassociated to each pixel could be detected, considering the highestpixel value as corresponding to the central point of the optical beam.In the case of a different concentration Conc 2 of the liquid solution,the refractive index of the solution itself changes: hence, if the angleof incidence of the ray R1 at the interface surface is kept fixed, theangle of the ray R2, and consequently that of the ray R3, correspondingto the case of the concentration Conc 1, will be modified, in the caseof the concentration Conc 2, as represented in FIG. 110 by the rays R2′and R3′. As in the case represented in FIG. 111, the ray R3′ will betransformed into another ray, similar to the ray R4, which will impingeorthogonally upon the receiver 44 ₂, but in a point different from theray R4, and consequently will light up a pixel different from theprevious one (the pixel that was previously lit up with theconcentration Conc 1 will be instead be off). In the case where the rayR4 lights up a number of neighbouring pixels, it will be possible todetect the various pixels and/or the corresponding signal intensity andto calculate the corresponding mean pixel or mean point. The variationof lighting within the linear or two-dimensional array of pixels enablesidentification of the precise position of the incident ray on thereceiver 44 ₂: in this way, it will be possible to associate to eachvariation of lighting on the pixels of the linear or two-dimensionalarray a given value that is representative of the concentration of theliquid solution.

From the foregoing description the characteristics of the presentinvention emerge clearly, as likewise do its advantages.

It is clear that for the person skilled in the art numerous variationsmay be made to the optical sensor described by way of example, withoutthereby departing from the scope of the invention as defined in theensuing claims.

The presence of an auxiliary or reference arrangement, aimed atdetection of at least one characteristic of a plastic material of thebody of the device, which for example vary following upon ageing orconditions of use, it is to be understood as autonomously inventive,i.e., not necessarily linked to the presence of a main optical-sensingarrangement, such as the ones including the emitters 42, 42 ₂ and thereceivers 44, 44 ₂, or else linked to the presence of atemperature-sensing arrangement and/or a level-sensing arrangement.

Such an auxiliary or reference arrangement for detecting thecharacteristics of the material of a body of the device 10 may be of anoptical type, for example of the type previously exemplified withreference to the emitters 42 ₁ and to the receivers 44 ₁ (FIGS. 84-89and FIGS. 90-99), or else of some other type designed for the purpose,such as an arrangement that detects the variations of capacitance and/orimpedance or of thermal conductivity and/or resistance of the materialof a body (such as the body 10 a).

As has been explained, the detections that can be made by the aforesaidauxiliary arrangement supply information on the state of a material ofthe body of the device, in particular of a material that is transparentor permeable to optical radiation. Information of this type is usefulfor the purposes of compensation of detections made using other sensorsof the device according to an autonomously inventive aspect, such aslevel sensors and/or temperature sensors, when the correspondingdetections are made in an indirect way, i.e., in the presence of a wall(such as the wall 20 or 21 of the body 10 a or the wall of the casing114 of the body 110 a) set between the sensing means (such as thetemperature sensor 19 a or the electrodes J) and the fluid (thesubstance or the ambient air) that is undergoing detection.

It will be appreciated, for example, that ageing of the material of theaforesaid interposed wall and/or the thermal stresses undergone by thismaterial may cause a variation of the characteristics of thermalconductivity of the material in question, which may adversely affect theprecision of temperature sensing. For this purpose, there could beenvisaged a reference arrangement of a thermal type, for examplecomprising at least one electric heater and one temperature sensor,associated to different points of one and the same reference wall.

Ageing and/or thermal stresses and/or alterations of the material of theaforesaid interposed wall may cause a variation in the characteristicsof electrical insulation and/or the dielectric characteristics and/orthe characteristics of electrical impedance of the material in question,with consequent adverse effects on the precision of detection if it isperformed, for example, via capacitive sensor means and/or level-sensingmeans with electrodes isolated from the fluid to be detected via a wall(such as the wall 114 and/or 120 of the body 110 a). For this purpose,there could be provided a reference arrangement designed to detect atleast a capacitance, and/or a impedance, and/or an electricalresistance, comprising at least two electrical conductors or electrodesassociated to different points of one and the same reference wall.

For applications of this type, the control electronics of the sensordevice is appropriately provided for compensating the detections made asa function of information acquired via the auxiliary arrangement andhence indicative of possible variations of characteristics of thematerial in question. For this purpose, for example, in storage means ofthe control electronics there may be encoded corresponding information,for example in tabular form and based upon empirical investigations,aimed at expressing the correlation existing between the referenceproperties of the plastic material considered (such as an opticalproperty, in particular its refractive index) and other propertiesthereof that affect a measurement for which the sensor device isdesigned (such as properties of electrical conductivity or impendanceand/or thermal conductivity or resistance). This information will beused by the control electronics, in particular by an electroniccontroller, for making the necessary compensations in the course of theaforesaid measurement, for example in the temperature- and/orlevel-sensing step.

Obviously, the auxiliary or reference arrangement may be provided in anysuitable position of the body of the sensor device that mounts it, inthe case of an optical reference arrangement of the type described, setbetween the corresponding emitter and receiver is preferably a part madeof the same plastic material as the one the characteristics of which areto be monitored.

As mentioned previously, the modalities for obtaining the supporting andelectrical-connection structure of an optical module provided accordingto the invention may be different and comprise, for example,overmoulding or coupling of one or more bodies of the structure on aflexible circuit support.

FIGS. 112-116 illustrate an example of a possible mode of implementationof an optical module, substantially of the type illustrated in FIGS.37-38, based upon overmoulding. In these figures the same referencenumbers as those of the previous figures are used to designate elementsthat are technically equivalent to the ones already described above. InFIG. 112, designated as a whole by 300 is a flexible circuit support orPCB, which integrates electrical-connection elements and, preferably,also connection terminals. For this purpose, the circuit support 300comprises a substantially film-like insulating substrate 30 ₁, forexample made of at least one polymer, such as a polyamide, or Kapton®,or liquid-crystal polymers (LCPs), or a polyethylene (PE), such as apolyethylene naphthalate (PEN) or a polyethylene terephthalate (PET).The substrate 30 ₁ is provided with electrically conductive paths, forexample made of metal or a metal alloy or a polymer with addition ofelectrically conductive fillers, which form the conductors 48 and 49 andpreferably also the terminals 50.

Identified in the circuit support 300 are a central part 300 ₁ and twolateral parts 300 ₂, 300 ₃. Located at the distal-end portions of thelateral parts 300 ₂ and 300 ₃ are the ends of the conductive paths 48,49 that are to be connected to the optical emitter and receiver, theends of the paths preferably being in the form of pads (notrepresented). Preferentially, the opposite ends of the paths 48, 49 arelocated, instead, at the central part 300 ₁ of the circuit support 300,in particular in the proximity of an edge thereof, to provide theterminals 50. In the example, these terminals are constituted by padshaving a central opening, which is coaxial with corresponding throughholes provided in the substrate 30 ₁.

In the cases where the optical module must be provided with apositioning opening similar to the one designated by 45 a in FIGS.36-37, the substrate 30 ₁ has a corresponding through opening 300 a. Inother embodiments, in which the aforesaid positioning opening is notnecessary, the opening 300 a may be omitted. In preferred embodiments,the substrate 30 ₁ of the circuit support 300 may in any case presentone or more passages, some of which are designated by 300 b and 300 c,through which part of the insulating material of supporting and/orpositioning bodies, which, as will be seen, are overmoulded on thecircuit support 300, is to penetrate and solidify. Preferentially, atleast one opening 300 b is provided in each distal end region of thelateral parts 300 ₂, 300 ₃ of the circuit support 300, as well as twoopenings 300 c at the central part 300 ₁, which are necessary also forproviding suitable openings in the central body of the electricalsupporting and connection structure.

In various embodiments, overmoulded on the circuit support 300 are oneor more bodies designed to perform the functions of the bodiespreviously designated by 45, 46, and 47. FIGS. 113 and 114 exemplify thecase of a supporting and/or electrical-connection structure 41 ₄, whichincludes the three aforesaid bodies 45, 46, and 47, which areovermoulded in respective regions of the circuit support 300, and inparticular at the central part 300 ₁ and on the distal end regions ofthe lateral parts 300 ₂, 300 ₃. For this purpose, as may be seen in FIG.112, the circuit support 300 is set in a suitable mould, having theimpressions necessary for definition of the profiles of the bodies 45-47(e.g., a mould substantially similar to that of FIG. 15, withappropriate impressions), injected in which is then the electricallyinsulating material necessary for formation of the bodies themselves,for example a polymer or a thermoplastic material. The aforesaid bodiescan hence be moulded so as to present the elements that have alreadybeen described previously: for example, at the central part 300 ₁, theremay be defined the arrest projections 45 b, as well as the upperformation 51 and lower formation 52, with the corresponding throughopenings 51 a, whereas at the lateral parts 300 ₂, 300 ₃ there may bedefined the seats 46 a, 47 a and the appendages 46 b and 47 b. In thecourse of moulding, the presence of the passages 300 b, 300 c of thesubstrate 300 ₁ (FIG. 112) enables the necessary flow of the injectedmaterial also towards the face of the circuit support 300 opposite tothe point of injection of the material and/or ensures—aftersolidification of the material—a solid fixing of the bodies themselveson the circuit support 300. In various embodiments, such as the onerepresented, the passages 300 c are also necessary for the purposes ofdefinition of the through openings 51 a. Preferentially, in variousembodiments, for the purposes of fixing of at least one of the bodies45, 46, 47 to the circuit support 300, moulded material is provided inthe passages 300 b, 300 c and on at least a portion of both of the facesof the circuit support 300, and/or moulded material is provided along atleast part of the edges of the circuit board 300 and on at least aportion of both of the faces of the circuit support 300.

Preferably, the lateral bodies 44 and 47 are overmoulded on the circuitsupport 300 so as to present, at the corresponding lower faces, at leastone passage, designated by 46 e and 47 e in FIG. 114, in order to leaveexposed corresponding regions of the circuit support 300 necessary forpositioning and electrical connection of the emitter and of the receiverof the optical module. In the case of terminals 50 of the typeexemplified herein, it is moreover preferable also for the lower face ofthe body 45 to be moulded so as to define passages that will leave alsothe terminals themselves at least partially exposed, as is clearlyvisible in FIG. 114, for example to facilitate subsequent operations ofsoldering of the wires or electrical connectors of the optical module.

After extraction from the mould, the structure 41 ₄ is as represented inFIGS. 113 and 114, and there can be mounted thereon the emitter 42 andthe receiver 44 a, 44 b, as may be seen in FIG. 115, which are connectedto the respective conductive paths 48 and 49, respectively, in order toobtain an optical module, designated as a whole by 40 ₄. The module 40 ₄may then be mounted at the corresponding optical site of the body of thedevice, substantially with the modalities described previously. In anembodiment of this sort, between the lateral bodies 46, 47 and thecentral body 45 there remain exposed respective portions of the circuitsupport 300, designated by 301 a only in FIG. 116, which is as a wholeflexible and/or deformable. By exploiting the flexibility and/ordeformability of these portions 301 a of the circuit support 300, thelateral bodies 46, 47—and hence the emitter and the receiver—may assumethe correct position with respect to the corresponding optical surfacesof the site (such as the surfaces 33 a, 34 a, visible in FIG. 19), asexplained previously, for example as a result of the thrust exerted bythe blocking and/or positioning member used (such as a member of thetype designated by 60 in FIG. 20).

Of course, the bodies 45-47 could have a configuration different fromthe one exemplified and be overmoulded so as to define also thinconnection portions, or in any case elastically deformable portions,which extend between the lateral bodies 46, 47 and the central body.

In further embodiments of the invention, one or more distinctpositioning and/or supporting bodies is/are associated to a circuitsupport. An embodiment of this type is exemplified in FIGS. 117-119,where the same reference numbers as those of the previous figures areused to designate elements that are technically equivalent to the onesalready described above.

With initial reference to FIGS. 117 and 118, in various embodiments aflexible circuit support 300 is used for the purpose, for example of thetype already described with reference to FIGS. 112-115, integrating theconductors 48, 49 and the terminals 50 in the form of electricallyconductive paths.

Designated as a whole by 41′ is a single body in which three upperhalf-bodies are identified, and in particular a central half-body,designated by 45′, and two lateral half-bodies, designated by 46′ and47′, which are to provide an upper portion of the supporting and/orpositioning bodies designated hereinafter by 45, 46, and 47. In theexample, the lateral half-bodies 46′ and 47′ are joined to the centralbody via at least one connection portion 160, preferably having arelatively thin and/or flexible configuration. The upper faces of thethree half-bodies 45′-47′ are formed so as to define the necessaryfunctional elements. For instance, with reference to FIG. 117, thehalf-body 45′ defines the arrest projections 45 b, the upper formation51, and the holes 50 ₂, as well as respective parts of the throughopenings, here designated by 45 a′ and 51 a′. The half-bodies 46′ and47′ define, instead, the corresponding seats 46 a, 47 a and appendages46 b, 47 b.

Designated, instead, by 45″, 46″ and 47″ are three lower half-bodies,which are distinct from one another, which are to provide a lowerportion of the supporting and/or positioning bodies designatedhereinafter by 45, 46, and 47. In this perspective, as is for examplevisible in FIG. 118, the lower half-body 45″ defines the formation 52,as well as respective parts 45 a″ and 51 a″ of the necessary throughopenings, as well as openings 170 in order to leave part of theterminals 50 exposed. The lower lateral half-bodies 46″ and 47″ areinstead configured substantially in the form of frames, each defining arespective passage 46 e and 47 e.

In various embodiments, the aforesaid supporting and/or positioningbodies, i.e., the half-bodies 45′-47′ and 45″ and 46″ that form them,are made of a polymer, such as a thermoplastic or thermosetting materialor a resin. Preferably, the material used is of a relatively rigid type,in particular if moulded with a relatively large thickness, for examplea thickness at least locally greater than 1 mm, in order to guaranteethe necessary supporting and/or positioning functions. The connectionportions 160 may be made of the same material and may be provided witharticulated joints or hinges, or else—as in the case exemplified—may besubstantially in the form of a lamina, or in any case with relativelysmall dimensions (such as a thickness of less than 1 mm) in order toguarantee proper flexibility. Alternatively, the half-bodies 45′-47″(and possibly the half-bodies 45″-47″) may be made of a relatively rigidpolymer and be comoulded or overmoulded on or associated to connectionportions 160 made, instead, of another, flexible, material.

In various embodiments, the half-bodies 45′-47′ and the half-bodies45″-47″ are provided with mutual-coupling means, for example snap-actioncoupling means and/or slot-fit and/or interference-fit means. In thecase exemplified, for instance, provided at the lower faces of thehalf-bodies 45′-47′ are projections 180 or seats 190, which are tocouple with corresponding seats 190 and projections 180 provided at theupper faces of the half-bodies 45″-47″. In various embodiments, theaforesaid seats 190 are through seats, but in other possible embodimentsthey may be blind seats. As has been said, preferentially, theprojections 180 may be coupled by snap-action in the corresponding seats190. It is also possible to provide further mutual-positioning elements,such as seats 200 defined at the upper face of the half-body 45″ (FIG.117), which are to receive corresponding projections 210 defined on thelower face of the half-body 45′ (FIG. 118), these seats and projectionsbeing designed to be located at the openings 300 c of the substrate 300₁ (FIG. 117). The projections 210 and the seats 200 may also be providedon the half-bodies 46′-46″ and 47′-47″, in particular in positionscorresponding to those of the openings 300 b of the substrate 300 ₁, asmay be seen, for example, in FIGS. 117 and 118.

The half-bodies 45′-47′(i.e., the body 41′) and the half-bodies 45″-47″may be moulded separately, being made, for example, of polymer, and thenbe coupled together, with interposition of the circuit support 300, onwhich there may previously be mounted the emitter 42 and the receiver 44a, 44 b, as may be seen in FIG. 118. For instance, with reference to thecase exemplified, the bottom face of the body 41′ is set up against theupper face of the circuit support 300 so that the positioningprojections 210, 210 a penetrate through the openings 300 b, 300 c. Onthe other side, the upper faces of the half-bodies 45″-47″ are set upagainst the lower face of the circuit support 300 so as to producecoupling between the projections 180, 210 and the corresponding seats190, 200. The presence of the passages 46 e, 47 e of the lowerhalf-bodies 46″ and 47″ enables pre-assembly of the emitter and of thereceiver on the circuit support 300. As has been said, in the caseexemplified, the projections 180 and the seats 190 are configured forsnap-action coupling, but the type of coupling thereof—as well as theirnumber and/or position—could be different.

Following upon coupling between the half-bodies 45′-47′ and thehalf-bodies 45″ and 47″ the optical module is defined, the structure ofwhich comprises the bodies 45, 46 and 47, each of which is formed by thecorresponding half-bodies 45′-45″, 46′-46″, and 47′-47″, as may be seenin FIG. 119, where the module is designated as a whole by 40 ₅. Also inembodiments of this type, between the lateral bodies 46, 47 and thecentral body 45 there remain exposed respective portions 301 a of thecircuit support 300 that are flexible or deformable, as well as theintermediate body portions 160, which are also flexible or connected inan articulated way. By exploiting the flexibility of these portions 301a of the circuit support 300 and of the intermediate portions 160, thelateral bodies 45, 47—and hence the emitter and the receiver—can assumethe right position with respect to the corresponding optical surfaces ofthe site (it should be noted, in this regard, that FIG. 119 simulates byway of example a condition in which the module is assembled), as aresult of the thrust exerted by the blocking and/or positioning memberused.

Obviously, instead of snap-action coupling means, and/or slot-fit means,and/or interference-fit means, the half-bodies 45′-47′ and 45″-47″ couldbe rendered fixed with respect to one another in some other way, withinterposition of the circuit support 300, for example via gluing, orwelding, or partial re-melting of the coupling means 180-210 themselves,if these are envisaged. It will moreover be appreciated that thepresence of the intermediate connection portions 160, albeitadvantageous from the production standpoint, in particular to facilitatehandling, and possibly useful for the purposes of protection of theconductive paths of the circuit support 300, is not strictlyindispensable for the purposes of implementation. On the other hand,where deemed preferable, also the half-bodies 45″-47″ could be joinedtogether to form a single body via intermediate flexible portionssimilar to the portions designated by 160. Intermediate connectionportions of the same type as the ones designated by 160 could, on theother hand, also be envisaged in the case of embodiments of the sametype as the ones described with reference to FIGS. 112-115, on the upperface and/or lower face of the circuit support 300, for example in thecase where it is desired to provide the module with a protection for theconductive paths.

It will moreover be appreciated that a flexible circuit, for example ofthe same type as the one designated by 300, could also be provided withmetal connection terminals 50 of a flexible type, for example of thetype described with reference to FIG. 7-9 or 91-93, in particular in thecase of overmoulding of the central body 45.

In possible variant embodiments, the body 41′ may be moulded with thehalf-bodies 46′ and 47′ already in a configuration inclined with respectto the half-bodies 45′, for example as in FIG. 119, in particularexploiting the presence of the intermediate body portions 160; possibly,for this purpose, also the half-bodies 45″-47″ could be joined to thehalf-body 45″ via intermediate body portions. Variants of this type maybe applied also to the case of an overmoulded structure of the same typeas those of FIGS. 112-116, in particular when the bodies 45-47 arejoined together via intermediate body portions.

Obviously, optical modules of the types described with reference toFIGS. 112-116 and 117-119 may be used in all the embodiments describedpreviously.

It will appear evident to a person skilled in the art that theindividual characteristics described in relation to one embodiment maybe used in other embodiments described herein, in various embodiments itbeing possible to provide a sensor device according to the inventioncomprising combinations of the individual characteristics describedpreviously, that may even differ from the previous examples.

For instance, all the various embodiments described may be implementedaccording to the teachings provided in relation to the embodiment ofFIGS. 72-78. Likewise, the solution that envisages at least one emitterand at least one receiver of a reference optical radiation withinterposition of a reference optical guide (such as the elementspreviously designated by 42 ₁, 44 ₁, 37 ₂, 35 ₂) may be implemented inall the embodiments.

In various embodiments, the closing or bottom structure of the body 10 acould also include a portion of the peripheral wall 20 of the housingpart 12 that projects towards the inside of the tank 1, or with thecorresponding outer surface in contact with the liquid substance. Inimplementations of this type, the optical arrangement for detection ofthe quality and/or other characteristics of the substance could beassociated to this projecting portion of the peripheral wall 20, whichwill be made of material transparent to the operating optical radiationof the optical sensor. For instance, with reference to the embodiment ofFIGS. 100-111, the seat 230 could be defined at the aforesaid portion ofthe peripheral wall 20, with the latter shaped to define at least thesurfaces 230 a-230 b (FIGS. 101 and 110).

In various embodiments, an optical formation or optical prism of thetype previously designated by 31, integrating at least part of thecharacteristics indicated in the previous examples, at least in parttransparent or permeable to optical radiation, is configured as adistinct or independent element that is mounted in a corresponding seat.For instance, the optical formation or prism 31, described withreference to FIGS. 72-78, could be a distinct element, like the shapedoptical insert 220 of the example described with reference to FIGS.100-111, whereas the corresponding seat 21 c could have a bottom walland/or walls that are transparent to optical radiation, like the seat130.

As has been mentioned, a sensor device of the type described previouslymay be obtained by making appropriate structural modifications (forexample, with a different angle c and/or using a different emitterand/or receiver), or else may be obtained in other embodiments and/orfor other applications, and/or may be used for detecting characteristicsof a fuel and/or for distinguishing mixtures of fuels, such aspetrol-ethanol mixtures or diesel-biodiesel mixtures, or else fordetecting possible contamination of a fuel.

As has been mentioned, a sensor device of the type described, comprisingan optical sensor for detecting characteristics of a substance, may finduse also in systems different from vehicles, which envisageinternal-combustion or endothermal engines, such as electric generators.

The invention has been described with particular reference to tanks andgeneric containers of a liquid substance subject to detection, but thesensor device described may be equally applied to hydraulic ducts inwhich the liquid substance is contained and/or flows: in thisperspective, the terms “container” or “tank” used previously must beunderstood as referring also to generic ducts designed to contain and/orto enable passage of the substance undergoing detection.

1. An optical sensor device for detection of at least one characteristicof a liquid substance, the sensor device comprising a device body havingan inner surface and an outer surface, at least one portion of the outersurface of the device body being designed to be in contact with theliquid substance and the inner surface of the device body being designedto be isolated from the liquid substance, wherein at least one detectionarrangement is associated to the device body, which comprises at leastone emitter and at least one receiver of a given optical radiation,wherein at least one first portion of the device body is made of amaterial suitable for propagation of the given optical radiation, the atleast one emitter and the at least one receiver being optically coupledto the inner surface of the device body at said first portion, whereinsaid first portion of the device body is shaped to contribute topropagation of the given optical radiation by refraction and/orreflection, from the at least one emitter to the at least one receiver,in such a way that the given optical radiation is at least in partpropagated through said first portion of the device body towards the atleast one receiver, at an angle and/or with an intensity that are/isvariable as a function of a characteristic of the liquid substance,wherein the detection arrangement comprises an optical module, whichincludes a structure for support and electrical connection of the atleast one emitter and the at least one receiver, which is configured asa part separate from the device body, and wherein the structure forsupport and electrical connection includes one or more bodies made ofelectrically insulating material associated, preferably toelectrical-connection elements made at least in part of electricallyconductive material.
 2. The sensor device according to claim 1, whereinthe structure for support and electrical connection includes a centralbody and two lateral bodies connected to the central body, there beingassociated to a first lateral body the at least one emitter and therebeing associated to the second lateral body the at least one receiver.3. The sensor device according to claim 1, wherein the structure forsupport and electrical connection comprises at least one of thefollowing: one or more bodies overmoulded on a plurality ofelectrical-connection elements; one or more bodies, which compriseselectrical-connection elements; a plurality of distinct bodies connectedtogether by means of electrical-connection elements; a plurality ofdistinct bodies associated to a flexible circuit support, whichcomprises electrical-connection elements; a plurality of bodieselectrical-connection elements moulded with an electrically conductivematerial comprising a polymer, said bodies and elements being co-mouldedor overmoulded on one another; a plurality of moulded bodies connectedtogether and capable of varying a relative position thereof duringassembly of the optical module on the device body.
 4. The sensor deviceaccording to claim 1, wherein the inner surface of the device body isshaped in said first portion to define a positioning site for theoptical module, the positioning site including at least one elementprojecting in a position corresponding to the inner surface of thedevice body.
 5. The sensor device according to claim 4, wherein at leastone body of the structure for support and electrical connection anarrangement for positioning and/or blocking with respect to the at leastone projecting element of the positioning site.
 6. The sensor deviceaccording to claim 4, further comprising a blocking and/or positioningmember configured as a part separate from the device body least and fromthe structure for support and electrical connection, the blocking and/orpositioning member being prearranged for engagement with the at leastone projecting element of the positioning site in order to ensurepositioning of the optical module.
 7. The sensor device according toclaim 6, wherein the blocking and/or positioning member comprises one ofthe following: a member which can be engaged by interference fit withthe at least one projecting element of the positioning site, by means ofan axial movement of said member with respect to the at least oneprojecting element; a member which can be engaged with at least one seatof the at least one projecting element of the positioning site by meansof an angular or rotary movement of said member with respect to the atleast one projecting element; a member which can be fixed in positionvia a corresponding stop element, which can be engaged with at least oneseat of the at least one projecting element of the positioning site; amember having an anti-rotation element, which is able to co-operate witha corresponding engagement seat defined in a body of the supporting andconnection structure of the optical module; a member which can beengaged with interference fit with at least one positioning and/orblocking element of a body of the supporting and electrical-connectionstructure.
 8. The sensor device according to claim 1, wherein the atleast one emitter consists of a single emitter of the given opticalradiation and the at least one receiver comprises at least two receiversof the given optical radiation which are set in positions generallyalongside one another.
 9. The sensor device according to claim 1,wherein the at least one emitter and the at least one receiver haverespective active parts for emission and reception, respectively, whichare generally directed towards each other and are set angled withrespect to one another, wherein at least one of: the at least oneemitter and the at least one receiver are arranged according torespective planes of lie that form between them a first angle that isless than 90°; two planes passing through the axes of the at least oneemitter and of the at least one receiver, respectively, form betweenthem an angle that is greater than 90°; an angle of incidence of thegiven optical radiation emitted by the at least one emitter with respectto a corresponding interface surface between the liquid substance andthe material of said first portion is comprised between 50° and 70°. 10.The sensor device according to claim 1, further comprising a shieldingarrangement for shielding any optical radiation that might alterdetections made via the detection arrangement.
 11. The sensor deviceaccording to claim 1, wherein the device body has a housing portiondefined by a bottom structure, including said first portion made of amaterial suitable for propagation of the given optical radiation, theoptical module being at least partially housed in the housing portion.12. The sensor device according to claim 10, wherein: the device bodydefines in a single piece the bottom structure and the peripheralstructure; or else the device body comprises a first body in a positioncorresponding to a seat or a through opening of a wall of a second body,which defines the peripheral structure and at least one part of thebottom structure.
 13. (canceled)
 14. The sensor device according toclaim 5, wherein the structure for support and electrical connectionincludes a single body defining at least one of the following: a centralportion having said arrangement for positioning and/or blocking; acentral portion having a side associated to which are both the at leastone emitter and the at least one receiver; two lateral portionsgenerally facing one another, with the at least one emitter and the atleast one receiver in a position intermediate with respect to thelateral portions; and two lateral portions generally facing one another,associated to which are an emitter and a receiver of an opticalradiation, respectively.
 15. The sensor device according to claim 1,further comprising an emitter and a receiver of a reference opticalradiation, and at least one reference optical guide made of a materialsuitable for propagation of the given optical radiation, wherein theemitter and the receiver of the reference optical radiation facerespective generally opposite ends of the reference optical guide, thereference optical guide being shaped to enable propagation of thereference optical radiation from the corresponding emitter to thecorresponding receiver.
 16. The device according to claim 1, wherein:the device body comprises, at said first portion, an optical guide whichis to come into contact with the liquid substance, the optical guidehaving a first end and a second end set apart from one another, the atleast one emitter facing the first end and the at least one receiverfacing the second end; or else the device body is shaped, in said firstportion, to define a housing seat for an optical insert having a shapedbody made at least in part of a material designed for propagation of thegiven optical radiation, and where: portions of an outer surface of theoptical insert face corresponding portions of an inner surface of thehousing seat; the at least one emitter and the at least one receiver ofthe given optical radiation face respective regions of the opticalinsert that are set apart from one another; the housing seat and theoptical insert are shaped in such a way that the given optical radiationpropagates from the at least one emitter to the at least one receiverthrough at least part of the body of the optical insert, through atleast one peripheral wall of the housing seat, and also at least in partthrough the liquid substance in contact with said peripheral wall. 17.(canceled)
 18. (canceled)
 19. An optical sensor device, the sensordevice comprising a device body having associated at least one opticalarrangement, the optical arrangement comprising at least one emitter andat least one receiver of an optical radiation and being provided fordetection of at least one characteristic of at least one from among aliquid substance, a material of the device body that is permeable ortransparent to the optical radiation, and a material of an optical prismor of an optical guide belonging or associated to the device body. 20.(canceled)
 21. The sensor device according to claim 4, wherein the atleast one projecting element of the positioning site comprises one ormore optical elements for propagation of the given optical radiation,selected from among at least one optical element defining two surfacesinclined in opposite directions, or a pair of optical elements eachdefining an inclined surface, and wherein facing one said inclinedsurface is the at least one emitter or the at least one receiver. 22.The sensor device according to claim 10, wherein the shieldingarrangement comprises at least one of the following: a shielding elementin a position generally intermediate between the at least one emitterand the at least one receiver, the shielding element being impermeableto the given optical radiation; a shielding element belonging to theoptical module; a shielding element comprising an intermediate cavity ofan optical element projecting at an inner side of said first portionmade of a material suitable for propagation of the given opticalradiation; an optical shield mounted at an inner side of said firstportion made of a material suitable for propagation of the given opticalradiation; an optical shield impermeable at least to ambient light andshaped to circumscribe at least in part a positioning area for the atleast one emitter and the at least one receiver.
 23. An optical sensordevice for detection of at least one characteristic of a liquidsubstance, the sensor device comprising a device body having an innersurface and an outer surface, at least one portion of the outer surfaceof the device body being designed to be in contact with the liquidsubstance and the inner surface of the device body being designed to beisolated from the liquid substance, wherein at least one detectionarrangement is associated to the device body, which comprises at leastone emitter and at least one receiver of a given optical radiation,wherein at least one first portion of the device body is made of amaterial suitable for propagation of the given optical radiation, the atleast one emitter and the at least one receiver being optically coupledto the inner surface of the device body at said first portion, whereinsaid first portion of the device body is shaped to contribute topropagation of the given optical radiation from the at least one emitterto the at least one receiver, in such a way that the given opticalradiation is at least in part propagated through said first portion ofthe device body towards the at least one receiver at an angle and/orwith an intensity that is variable as a function of a characteristic ofthe liquid substance, and wherein the at least one receiver of the givenoptical radiation that is at least partly propagated through said firstportion of the device body comprises a first receiver and a secondreceiver.
 24. The sensor device according to claim 23, wherein thedetection arrangement comprises a control circuit arrangement configuredfor detecting, based on output electrical signals of the first receiverand the second receiver, a possible variation of a critical angle of thegiven optical radiation which is representative of a variation incomposition or concentration of the liquid substance.